My Jeanie Rub machine is about 25 years old and
The chances are that some parts are worn, after all this time, or the motor is going bad, but you might get lucky. As far as taking the unit apart, you'll be hard pressed to find any directions. Best thing to do is just study the machine- everything that went together has a way to come apart, even if it has to be broken, which some things are designed to do, upon disassembly. However, most things can be taken apart with the right tools and patience. Look for screws or hidden fasteners under label plates and covers (some will snap off, as they are pressure fitted). Sometimes special tools are required or the fastener is impossible to take off without breaking something.
Sometimes it's best to get advice from someone who does this type of thing for a living- that is, a small engine repair shop. They could probably look at it and tell you what needs to be done, or at least what you need to do to get into it.
Anyway, good luck, study it well, and hopefully you'll be successful getting it fixed.