The mechanical problem is that when I disengage the motor to wind a bobbin, the needle bar still runs most of the time, especially at full speed. Is that an issue with the washer behind the middle part of the wheel or something else? Yup you got it - flip it over - I think there must be different ways the dumb things can go - then when you do get it all lined up it slides out so you have to fiddle with it - think of all the money you are saving by not paying someone in a shop to fiddle with it...
As far as stitching, I *think* I've got two problems going on at once. First is that I suspect my bobbin case is worn out. When I insert it, it immediately flops over instead of the arm staying right at the notch. Am I correct in thinking that once the case is clicked into place, it should stay put rather than rotate?? Does it actually click into place - some of them have to get pushed on pretty good so seat right. If it goes in it probably is the right one. What about your bobbin - does it fit right? Is it the right bobbin? I can see that if the bobbin is a hair too big - it won't go all the way in. You cleaned the lint out of the bobbin case didn't you? Maybe something in the shuttle race?
My second problem is thread nests which I know is usually an upper tension issue. When I watch the shuttle during stitching, I can see the upper thread get caught on the bobbin case and wad up. I hope that once I get the loose bobbin case figured out, the thread nests will resolve or only require some tension adjusting. Does that sound plausible? Don't do anything about this until you get the other problem fixed. I just fixed up a 319 that was making some doozy loops - it was the little finger holding the shuttle too tight - thread couldn't pass through. I knew the upper tension was right and the bobbin tension was right so I started looking for burrs and that was what I noticed.
Maybe somebody smarter than me knows something I don't.... anybody else got ideas on this one?