I have an old Singer 29K57 patching machine. It was in a barn for over 2 decades and I have been fixing it up to use. I replaced several parts, cleaned and oiled it all up and got everything running smoothly, with one exception... the bobbin keeps jamming.
I have been a professional sewer for many years (although new to this kind of machine). I've switched needles (different sizes, etc.), switched threads (including different weights), purchased new (used) shuttle carriers and tension springs and new shuttle bodies.
The timing is right. The shuttle is picking up the thread with every loop. For some reason, however, the thread slips under the shuttle carrier and gets jammed (see image).
I watch it very slowly and still can't figure out why it's doing it. The first loop through, up to about 2-3 stitches, seems to go smoothly but then it jams again.
Any thoughts? I almost threw the whole thing out the door today!