[Milsurplus] Fixing up an I-177B tube tester

[Ian Wilson]

I cleaned the wafer switches with an aerosol switch cleaner.
Now there is some life but still bad news:

In Tube Test position, when I depress the AMPL switch, the
Fuse light comes on brightly and the meter makes a loud buzzing
noise. The average position of the needle is about 1/4 way up the red
region.

This happens whether I have a tube in the socket or not.

 I have things set up for testing a 12A6 (not that it makes any difference).

With power off, the resistances around the rectifier sections and the L/R
pots
all seem consistent with the schematic.

Any ideas what to look for?

73, ian K3IMW