Stop Motion knob issues...
 

I think almost every machine I have worked on cleaning, oiling, etc. has given me trouble when I put the hand wheel back together. I have even taken photos step by step as I take them apart to clean and oil, and apparently (as far as I can discern,) get them put back together exactly as they were originally. Yet, the stop motion action doesn't work when I twist the knob. I have taken them apart numerous times, tried different positions, and still can not get the stop motion part to disengage the needle bar.

I have followed (I thought!) tutorials, diagrams, Tools for Self Reliance book...

Any suggestions on what I am missing/doing wrong?! I have read some people online that say sometimes you just can't get it to work, and then don't worry about it.

Are you putting the winged washer ears out?

Yep. I can not think of a single thing I have not tried... ;)

But keep suggestions coming in case there is something I have NOT tried. Thanks.

It's either the washer is installed incorrectly, (I invariably have to take everything apart and rotate the washer 180 degrees), or the shaft and/or center hole in the handwheel needs cleaned and/or oiled/greased.

There really isn't much else that could go wrong.

I would make sure that the handwheel spins freely on the shaft before you put everything back together.

Okay, I'll try spinning the hand wheel before reassembly...

Often the washer will slide off slightly as you try to screw the stop motion knob back on and it isn't always obvious which makes it not seated correctly and won't work. You could try sitting the machine up on its nose (held upright with one hand) as you place washer and screw knob back on. Of course, that only works if it's not installed in a cabinet. Alternatively, try holding the washer in place with the tip of a flathead screwdriver as you screw knob down.

Did it work before disassembly? I have a Kenmore whose stopmotion wouldn't work but it was a stuck secondary pulley and it worked after cleaning that...so there are some exceptions.