mme3924,
Our T&S is a 778. We got it in trade. It's been updated with spiral cut gears and actually sews quite well, except for the problem of ejecting certain white cams. I've got a tip from my LSMG and as soon as I get to the machine to try it I'll report back.
I sometimes think the problems with the plastic geared machines was more operator caused than the gears. Some people just tend to abuse things, or work them to death ( my wife for instance ).
I wish I could find some steel gears for her 538, she'd be in heaven then.
Joe