Thanks to all of you! The backstitch is now working! I still don't know what was causing the problem, because by the time I got the plastic cover off the end where the hand wheel is, it had started working again, probably because of all the manhandling I gave it. Anyway, I got an interesting view inside my machine and gave it a really thorough cleaning and oiling and she is sewing beautifully now and I am happy. Thanks again!