[Test-Equipment] Weston Tube Tester

[N4ue@aol.com]

Hi all. I have a beautiful Weston Model 981 (Type 3) Tube Tester. 
Unfortunately, it's not working 100%. The 'leakage' function seems OK, but the Gm test is 
inoperative. The problem appears to be that the internal 5 kHz oscillator is 
not working. When the Gm switch is operated, B+ is being applied to the osc. 
tube (which checks OK on another 'emissions / short / leakage' tester. I 
replaced all the caps, as I routinely do on gear this old and it made no difference.

Does anyone have any experience with one of these and might offer assistance 
of where to start. I do have the manual and schematic............

Thanks!


Ron

N4UE