$20 is a good deal,yes there are quite a few different factories these are made & the quality can very,some even come from the factory Sailrite gets them from but it's hit or miss to figure out which brand is best.One thing about Sailrite is they are also a "clone" of the old Thompson machines from the 1970's & they do buy them from a factory that makes a better quality.
This is normal,there is a finger that sets in the groove of what we call the hook basket,it has to have some play to allow the thread to travel through.Put the bobbin in,thread the needle & turn the machine slowly & watch what happens it will help you to understand why it needs the play.The biggest problem with these machines is the lack of oiling the ridge on the hook basket causing it to bind up.
I've never seen one that wasn't adjustable.Look in this attached file.It's the same is Singer 111w,211w,Consew 225,226,255,Juki 562,563.
441 top feed cam.pdf
I've found it's not good to buy a cheap hook,you get what you pay for,stick with a Hirose or Cerlani they should be close to $150.00,there are also some Juki 563 saddles on ebay that you should buy & then you won't have to machine yours.
I've wondered why myself & was always told they were made for sewing the vamps on a shoe.But it would be hard for a right-handed person to sew with so maybe they were specially made for left-handed people to sew in the shoe factory?
David,Looks like it's stitching pretty good.I wished I kept ser# of the Landis 3's I've sold over the yrs, because I'm almost certain I painted & sold this one many years ago,we used to paint alot of them this color & also used angle iron to hold them to the table.And we had a fellow come in one time that looked @ some machines in the warehouse house while any guy was there alone & alot of the plates & shuttles came up missing after he left, so we had them made up in bronze like this one has.
I can't tell you what was in someones head when they did this because I don't know of any reason other than maybe the last belt fit loose so they "tried" to make it tighter.I would take a Dremel & grind off the high points of punch mark & called it fixed.
I was working on a machine last Sat. that needed one & found out we are out of them,I will be ordering more soon.It is screw #200082.Here's a parts list for the machine herehttps://www.supsew.com/download/Singer/Singer 111W155.pdf
The stitching looks pretty good.Here's a pic of the collar on the inside of the handwheel it's just alittle under 3/8" & also a pic of the standard old style of hinges for an industrial machine,while the ones you have will work they are for a home machine & the pivot pin is much thinner.
111w flywheel.html
It's odd you have that much shaft sticking out,it's usually flush.There is a collar cast into the other side of the pulley is it on there?Yes the 2-screws are all that holds it to the shaft.
On the backside of the machine there's a wingnut adjustment that has L,M,H loosen the wingnut & move it so the line is on the H & report back what happens.