Hickok 539A issue

[928GTS]

Hello everyone,I recently picked up a Hickok 539A and it seems to work well except for the following issue:

When the suppressor switch is in position two:

- I lose bias voltage when the shorts selector is in "tube test".
- The shorts light illuminates in all positions except one.
- The following voltages are present during a tube test:
(Setup for a 6V6 using pin 8 as a ground)
Pin 1: 0VDC,3.3VAC
Pin 2: 0VDC,3.3VAC
Pin 3: 197VDC,24.8VAC
Pin 4: 137VDC,37.2VAC
Pin 5: 0VDC,0VAC
Pin 6: 0.35VDC,7.86VAC
Pin 7: 0VDC,3.26VAC

- The following voltages are present during a shorts test:

Pin 1: 0VDC,0VAC
Pin 2: 0VDC,3.2VAC
Pin 3: 0VDC,0.77VAC
Pin 4: 0VDC,0.77VAC
Pin 5: 0VDC,0VAC
Pin 6: 0VDC,10VAC
Pin 7: 0VDC,3.2VAC

When the cathode selector is in position two:
- I lose bias voltage
- The shorts light does not illuminate in any position.

I've tried cleaning the sockets with some contact cleaner to no avail. Changing any of the other selector switches has no effect on the above issues. The 83 and 5Y3 have been swapped in from a known working unit.

Any ideas?