Ok, I'm back home and the machine, on the frame, is working as it's supposed to! Mr Stewart, an ancient man who owns the LQS and has been in the sewing machine business since before I was born, sat down with me and helped me to learn what to look for. It turns out that he's the one who originally taught Wendy Butler Berns how to machine quilt!
Anyway, my needle, face plate, bobbin and case were all properly threaded and working, no burrs etc. He said that 90% of the thread breaking problems could be traced either to the way the machine is threaded, or to the spool of thread itself. Both of the spools of thread that I'd been using were spools I purchased on sale at a booth at the Chicago Quilt festival back in April - and both had issues with how they were wound on the spool. He showed me how to set up a spool that had some issues and how to watch for any kind of 'catching' or resistance from the spool as the thread plays out, and how to determine, before I buy thread, if it's properly wound with the right number of strands in it.
YYAAYYYY. TY for the prayers and wishes - I only had time for 10 minutes of quilting after all that, but it was flawless quilting!
Musicmaker, who doesn't mind the issue being user error as long as there is a solution for the user!!