I don't work on these things but a friend asked me to check out his 1266 after refusal by Fisher to supply parts. I'm sure other techs might have a better method but here's what we did.
Problem: No Test Tone, no power to the unit (broken diode lead)
Problem: Broken Sensitivity control
Concerning the control replacement: Fisher was contacted and asked if they had the control in question. Their reply:
Problem: No Test Tone, no power to the unit (broken diode lead)
Problem: Broken Sensitivity control
Concerning the control replacement: Fisher was contacted and asked if they had the control in question. Their reply: