I have an OTC dial back that goes awry and another digital one (made by OTC as well) with a tach that gets funky on occasions...
I would like to know how to fix or send them back to OTC for repair.
Probably cheaper to buy another one than send back. Seems like if you send something back for an intermittent failure they won’t find it and will just send it back to you, unless you are lucky and they send you a new one. You eat the postage and fees and get nothing.
You may be able to take them apart and spray the switches ( and probably all of the insides) with some contact cleaner. Most of the time it seems like it is the moving parts that go bad.