i think the OP is referring to a "chrome box", not a late model computer control unit. [if i'm wrong, please correct me !]
if so, other than swapping out the round gizmo on the face, [i forget what it's called] they are not generally worth messing with.
by the time you remove the potting material on the back side, and screw around checking all the diodes, resistors, and solder joints, then fixing what you can, you might just as well buy a new unit if you can find one.
basically just not worth the time and effort to repair, just to try to get a few bucks out one.
just an old man's opinion. your mileage will vary.