7A11/Repairs
Symptom: Readout always displays IDENTIFY. Key in the probe is OK as checked with an ohmmeter.
Problem: No contact on NC side of the microswitch behind the position control.
Solution: As it is not practical to get contact cleaner into the switch, I disconnected the switch and exercised it a few times while connected across a lab PSU set to 20 V, 0.5 A to burn off the oxide layers.