We used to restore machines like this monstrosity. They are soul destroying to work on as you get them back into shape, turn them on for the first time and hear multiple problems. You then end up taking them apart again. The hole in the cabinet to accomodate the flywheel is a strong indication that all is no right. I wouldn't necessarily trust the capstan. It's all restorable but life is too short. Unless it goes for $500, leave well alone because you are going to spend a fortune.
Uncle Martin