On Saturday after I shared my poor, pitiful story, I had to put everything back together, so I thought I'd take one more crack at fixing my machine. I paid very, very close attention to what exactly what was going wrong, realized the thread was catching in two separate spots, and decided if I could tweak those little spots just a hair, it might help. It certainly wasn't going to make things worse, and after all, I only needed enough give to get a piece of thread through. So I used the screwdriver that came with the machine, pushed just a bit (not hard enough to visibly move anything), then tried it again. Magic! So I'm not certain exactly what I did, but it's sewing just as good as new now - nice and quiet and I've got the tension turned back down to a 5 & it's sewing beautifully. I think I'll probably still take it in at some point just to get tuned up, but at least now it's not a necessity. Yay!
Overall it's been a great sewing weekend - I fixed my machine and got some good stuff finished up, but more on that later this week.
And thanks again for all your great advice & tips, you're all wonderful! :)