If this unit has been sitting unused for a long time it may just be dirty or have oxidized contacts. The easiest thing to do, and some times very effective, is to exercise all the switches and controls. Just cycle them back and forth until your wrist get tired. Don't forget the little slide switch on the side for the "direct/coupled" feature. Also, turn it on and off repeatedly. If the protection relay contacts are dirty, that can give you meter and output problems and cycling the unit on and off will exercise the relay contacts.
The next step would be to get a can of Deoxit and clean all the switches and pots. Be sure to let it dry out before you turn it on.
If the problems don't change after doing all this, then you can start asking about repair.
- Pete