Uwe

Post some picture before you start taking things apart. If you're unsure whether you have a clutch motor or a servo motor, I'd recommend taking a step back and evaluate before you start digging in. General rule: don't turn a screw unless you know what it does (unless you can afford the machine to be down for a week or two while you figure out what went wrong.)

You can move the speed reducer pulley toward the back. There's a bit of science/geometry to installing motors and speed reducers. Tilting back of the machine is part of it. When installed just right the tilting works like it does without the speed reducer. Essentially, when you draw an imaginary line through the hand wheel and the hinge pivot, the center of the connecting pulley (speed reducer or motor) needs to be slightly towards the back of that line. Otherwise you have to overcome increased tension at first when tilting the machine back. There's nothing you can do about the position of the hand wheel and hinge pivot, so the only thing you can adjust is the position of the pulley. Here's a quick diagram that hopefully illustrates the concept. Green pulley (or motor) position is good, red position is trouble when tilting the machine back. The graphic exaggerates a little. Pulley on that line or slightly behind is fine. In the red pulley position the distance between hand wheel and pulley (and thus belt tension) increases at first, then decreases as you tilt the machine back. In the green position, the distance between hand wheel and pulley only decreases (reducing belt tension) as you tilt the machine back.

When you manually back-tack you slightly raise the feet to turn the material around 180˚. What they mean is that thread tension should not release when you lift the feet only slightly for that purpose. Some chain stitch designs are technically incapable of sewing in reverse (and it's not a question of reversing material transport like with lockstitch machines.)This has to do with how the thread loops/triangles underneath are formed. On some chains stitch designs the chain can only form if the material moves in one direction.

Yes, "441" is shorthand for a class of machines that includes the original Juki TSC-441 and the many copies, clones, and close variations of that design.

That flatbed table sure is bigger than mine! Seiko makes good machines. A good used original (Juki,Seiko,Adler,Pfaff,etc.) is worth as much as a new clone - and will likely hold its value better, at least in my book. The 441 is the more popular design, more people have experience with it, and you may have an easier time finding help, parts, and accessories for it. Most people cannot tell if a stitch line was made on an original or a clone, but some people find working with originals more enjoyable and rewarding.

I recommend ordering bobbins by part number. Don't trust the "Fits XYZ machines" statements (your bobbins "fit" but they're not right.) Get some original Juki bobbins to do your machine justice - how much can they cost, really?

Sounds like your bobbin basket got forcefully rotated out of position and jammed up pretty well. If the bobbin basket rotates out of position, the needle will surely find an early demise. Normally that bobbin basket will only properly lock into place in exactly one position. If it's not inserted properly and the latch key that keeps the basket from rotating is not properly engaged in the matching cutout, the basket may spin out of place and bind up. I made a video that hopefully will illustrate what I'm trying to say:

The phenolic plywood does not lend itself to glueing because nothing sticks to that slick coating. So screws it is, and lots of them. Makes for a very solid table top, though.

I built a table for a sunken 5-thread Juki MO-816 serger for a client. Not precisely a leather machine, but a rather challenging table to build. The tabletop and suspended shelf are made of two layers of 3/4" plywood, phenolic and baltic birch plywood, screwed together. The black laser-cut acrylic rings on the suspended shelf keep the machine's rubber feet in place to keep the machine from wandering as you sew.

Just for the record and to keep rumors from spreading, the CB3200 is NOT a clone of the Adler 205. The CB-3200 is a well-loved mutt that incorporates some elements of the Juki TSC-441 design along with other design elements of undetermined lineage. No Adler 205 plans were harmed in the making of the CB3200. The barrel hook may be interchangeable, but that's about it.

Then a proper motorized sewing machine should appear to be a bargain, not "crazy expensive."

Good old Dixie Sewing Machine to the rescue! A website design that predates Google/Facebook/MySpace and hasn't been changed since, but with a treasure trove of manuals. Hard to believe, yet fitting, that Pfaff uses them as their go-to online resource. I've been there many times and have downloaded entire sections of manual because that website may disappear at any time without notice, along with all those manuals. I actually had those file hiding on my own archive. Thanks for sharing the links for future inquiring minds!

Can you please share the Pfaff 337 PDF manual(s) here ? One of the administrators (green username like @Northmount ) can help if the file is too large. Just the link to the PDF would be great, too, if its public.

I'd recommend making a day trip to Keystone Sewing (LW member @Gregg From Keystone Sewing ) in Philadelphia. Having somebody available local-ish for advice, parts and service can make a huge difference. Being able to see and try out a machine in person with your sample materials is a big deal. Online info generally doesn't tell the whole story. I also think the kind of machine you probably want for shoe work is a dual driven wheel setup. Some of those machines belong to a class of clones that often have "9910" in the model number. This is the Highlead GC24618 (HG9910) in Gregg's shop. Once your shoes sell like Jimmy Choo, then you can afford a proper modern machine like the Pfaff 1591:

That speed reducer box alone sells for close to $180, so you got yourself a good deal. It looks very much like a Consew 206RB-? to me. Exactly which model level 1/2/3/4/5, I can't quite tell. With a little luck ,it's a re-badged Seiko STH-8BLD. If so it'll say Seiko all over the place on the inside. Most people in north America refer to that hook as a horizontal axis hook, using the orientation of the hook's axis to classify. Elsewhere in the world they use the hook's plane of rotation as the reference, which is indeed vertical. I'm just now reading a book from the 50's where the German author constantly uses phrases like "horizontaler Greifer (vertical hook)", in order not to confuse "die Amerikaner." I generally add the word "axis," as in "horizontal axis hook" to remove any ambiguity and avoid repeated "your horizontal is my vertical" elaborations.

You should totally buy a machine from a local store if you can. They'll be happy to provide service and parts. The early Consew 206RB-5 and previous 206RB-1/2/3/4 models were Seiko machines. Later, Consew quietly switched the 206RB-5 to a Chinese clone supplier.

My Seiko CW, LCW, NCW Operator's Guide (Seiko CW, LCW, NCW Operator’s Guide.pdf) covers multiple machines. The oil reservoir segments only apply to the LCW version, which, as @brmax already pointed out, actually does have an oil reservoir. The CW version does not have an oil reservoir. Here's the segment talking about the oil reservoir on the LCW:

All in the list except the Consew 206RB design have vertical axis hooks. If there's a rectangular slide cover plate to the right of the feet, then it has a vertical axis hook.

This may be an uphill and loosing battle. Remote crowd sourced support, being new to sewing, dealing with a mystery machine that has experts guessing at the most basic information is not an ideal combination. I predict lots of frustration all around. Post some detailed photos (good luck figuring that out on this forum) of the machine including any markings or brand stamps you can find on it or on parts inside or under the machine. Your only real hope may be to find out who actually manufactured the machine and what the original model is. Consew doesn't manufacture machines, they only put their label on machines made by others (Seiko etc.) - and obfuscate documentation to render it nearly useless. If you can find out the original make and model, you have a chance. Otherwise, you may be better off starting with a different machine.

The Consew 310 looks to be a bottom+needle feed design, based on the Consew 310 parts diagram. Not a bad starting point for leather work. Finding parts and service information for this oddball machine may be hard. The fact that the parts book doesn't even tell you what needle system to use is not encouraging. Hopefully the machine came with a pack of needles or a sticker that indicates the needle system. Since you already have the machine, the best way to find out if it will sew 8-10 oz leather is to just try it out. Get some leather point needles of whatever mystery needle system this machine uses and experiment.

And taking inflation into account, that $2,200 in 1990 is roughly twice that today. So the USD $450-ish price for that LU-563 is roughly 10% of what it cost when new. Sounds like a bargain to me.

Here's a nice heavy-duty table-top sewing machine you can operate by hand - the Consew 733R. It even has reverse. It's also quite portable - if you're quite strong

A Juki LU-563 in good working condition is a steal at CAD $600 (USD $456). That machine may well be gone by the end of the weekend. If I were you, I'd go pick it up NOW.

That $6,700 price tag is likely referring to the new Juki LS-2342, but a typo crept into the model number. It happens . . . a lot.

The modern version of the Pfaff 337 lists a max stitch length of 3mm of the lower feed dog and 6mm of the upper feeding foot. The english version of the manual is plain wrong - the German version talks about 3mm lower and 6mm upper fabric transport. There is only one feed dog. The upper feed can be adjusted smaller to match the feed dog at 3mm max., but you can't adjust the feed dog feed movement up to match the upper maximum feed of 6mm. You could, theoretically, remove the feed dog and only use upper feed, but that's unlike to give satisfactory results. Your type plate also shows "BS N 36". The "S" simply indicates fabric (Stoff). I doubt they ever made a leather version of this sleeve setter. Here's the english (wrong) spec page: Here's the original German spec page: Don't be afraid to start a new topic. This Pfaff 337 info doesn't really belong in a topic about the Pfaff 335.