Constabulary

I´d try this by hand cranking the machine but again the needle hole has to be wide enough for 2 thread strands + needle. 214x1 / 328 needles have the same dimensions as 216x1 and I´m using the 214x1 in my machine w/o problems. 216x1 has a slightly different needle tip they have some kind of channel in the tip - not sure why. In case the hook tip hits the needle you have to move the hook a bit to the right and probably the bushing of hook driving shaft too. But it depends on how the machine is set up. Back in 2015 when set up my long gone 133K I started this topic:

why is the bottom thread under the latch of the bobbin case? Always good to read the manual fully (no offense) - I guess you have a manual, right?

The resistance probably is when the foot lifts up cause it then is working against the foot pressure spring. The higher the foot lift is set and the higher the foot pressure is the more resistance you feel. Just my thoughts. I´m not in front of the machine.

is it just me or does the cam track look concave? It should not look like that, right?

basically it depends on the size of the needle hole in the needle plate. I never tried to max out what it can sew but 207 / 277 thread with # 24 /25 needle is not a problem with mine.

You can use other needles systems but you have to adjust the needle bar height. I´d be glad if I could find a 97 on my side of the pond. 😁

https://www.ebay.com/itm/157174686380 Not mine (obviously) but could be interesting for some folks in the US. Ex factory it is a straight stitch and cam controlled 3-step 8mm wide ZZ machine (subclass 135). It shares presser feet, feed dogs, needle plates and probably some other parts with its "older sisters" like 107w, 143w and the like. Found it as I´m about repairing one and looked for information cause I have one here that needs a new cam. 🤥

If it was me I´d check with a professional leather cleaning / restoration service. DIY like "vinegaroon'ing" may work but it could get worse also. Again, I´d check with a Co. who is restoring / reconditioning leather. If you have one locally they may come to your house and check the damage. May cost some $ but a new leather couch most likely is more expensive. Not on my end of the world but these folks f.i. offer telephone support: https://clydesleathercompany.com/pages/about-us

Needles should be system 88. Not sure which manual you have but this one (German Language) should be fairly close: Claes+Elastik+I+u+III_cleaned.pdf

just figured I could be wrong with that - just found this thread regarding a 105-27 and it seems to have screws in this subclass. 😉

some more Hope the pics help setting up yours. Mine still has thee original clutch motor but your seem to have a modern servo motor alreday. If you need more detailed pictures let me know.

Here are some pictures of my 8346-30. BTW when you look at the data plate the number below "BAUJAHR" is the year when it was made.

what I have noticed so far is: The needle plate / throat plate seems (!) to be modified and an the needle plate is missing material (or a deflector cover) left side of the roller foot / feed dog. Maybe this is something custom made but I can`t tell from the pictures. Not sure why this is but it is / looks unusual IMO. BTW - the original 105-27 came set up as jump foot machine and not with roller foot. So seems your machine has been modified quite a bit. But this could be custom made and I don´t want to judge this but it is not how the machine left the factory. In your video it seems (!) that 2 thread guides are missing, one on the needle holder (seems to be ground off somehow) and one on the face plate. Therefore the thread is "bouncing" around. This may affect the loop forming and that could cause thread breaking. EDIT I: Some one has modified the shuttle race as it seems. Your is held by 2 screws (maybe they are too tight???) but originally it has a U shaped sheet metal leaf spring that is holding the shuttle race in place. But again - could be a modification a customer asked for. Hard to tell w/o knowing the history of the machine. EDIT II: some pics of how the thread guides look on an Adler 104

just found a thread from 2024 regarding the Adler Roller Foot. https://leatherworker.net/forum/topic/120449-help-needed-_-cant-find-roller-foot-for-45k89/ Old parts number for the roller foot was 06422 - new parts number is 104220124 College sewing in UK had them (out of stock): https://www.college-sewing.co.uk/104220124-roller-foot-durkopp-genuine.html but sit down before you click the link 😉 (as I said before) Back in the days when my interest in sewing machines started I needed a slide plate for an Adler 104 flat bed machine and IIRC they asked 50€ + tax and shipping but that was w/o spring and and screws. That was just one "Adler parts situation" and soon I figured that certain Singer parts (and their clones like SEIKO f.i.) fit for certain Adler machines as well cause Adler back in the old days copied a lot of parts from Singer 45K´s 😉 That was the time when I discovered College Sewing in the UK and their wide range of Singer parts.... (and Seiko, JUKI.... who cloned Singer and so forth....) So guess why this guy from the land of Pfaff and Alder is so Singer crazy. It´s because of Parts Parts & Parts. But Brexit changed a lot but I´m still Singer crazy.... Still for the same reason.

what Wiz said! The above linked roller foot will NOT WORK. But OEM Adler 4, 5, 104, 105 roller feet will work but they cost big $$ We had this topic before: