Standard Class "P" help, please
I've been lurking lately, trying to get back into sewing machines, and I picked up a pretty little Standard Class "P" treadle. The table and irons were in great shape, but the head was filthy. I got it cleaned up, but it won't sew. Or rather, it won't as long as there's fabric under the foot. Testing it without fabric and the shuttle picks up the top thread from half to most of the time; try to test sew on fabric and it's none of the time.
It looks like, when the needle starts to rise, the thread doesn't make enough of a loop (or any, with fabric) for the shuttle to pick up. The shuttle fits tight against the slide, so it's not missing the thread, the thread just isn't coming out of the thread groove on the needle far enough to be picked up. As far as I can tell there's nothing to adjust (although I may be wrong about that), so now I'm at a loss. What am I missing, or what should I adjust?