I do have a user's manual. No Service Manual (but that's probably going to be an impossible task). I'd been just going through the machine with the "that can't be right" checks. Despite the lack of information, I've been able to fix the Drive Wheel Disengage, Timing, Thead Tensioner, Presser foot tensioner, and rewired the motor. I'm still looking for the "real replacement" drive belt. I am thinking maybe a 13 would get it done... I know the one that's on it is just way too long. My current project is the feed dogs. They operate just fine for normal, but don't drop for silk or darning settings... but she will eat projects like no one's business. I have a feeling that she's going to be getting a whole new wooden travel case shortly... I don't think I've owned a machine that felt this bullet proof, and it matches the paint on my 56 Nash Metropolitan.
I've been trying to figure out what feet I can run with the left homing needle... that's pretty much a pain in the rear and quite difficult to see where the needle hole is and/or if the foot is designed as a zig zag from most websites. I did find a website in the UK that claims they have the presser feet for the MZB. And they did say they have the straight stitch foot, which is awesome. Just need to locate a new plate for straight stitch to go with it. I'd rather not go overseas to get them, but beggar's can't be choosers.