Jobo does still exist, and they do have parts for some units, though they haven't made the CPE for some time. However, as a guess, a motor for your unit, if they have one, might cost as much as you've paid. If you can't settle with the seller, your best bet is likely to see if the motor can be lubricated, or serviced.
If it works well when the unit isn't heated, then using it at room temperature might be an option, unless you are planning to use it for color.
If the seller won't settle, see if he can give you information as to the unit's history. That might help in diagnosing, or figuring out a plan of action.