Thank you for all your suggestions! Especially about taking lots of pictures!! I PM'd Candace and she graciously sent me more ideas of things to look for. I've gotten to the point where I believe the problem is, in fact, one of the nylon gears is cracked, or that it is just seized up in a place I can't pinpoint. So, boo-hoo, I'm going to take it to the shop. It was fun looking through the machine and seeing where things come together and sort of figuring how it works, but this is beyond me. Wish I had someone around who could teach me some things - I've got a Morse SX-4000, a Necchi (can't remember which number, but newer), an Italian Necchi Supernova, and an old Kenmore waiting out in the garage! I was told that the Kenmore works, but haven't looked at it yet - weighs about 400 pounds, I think.
I think I'll rest a couple of weeks and maybe actually do some sewing before I start the next one!
Thanks again,
Margaret F