Backhand writes:

I have a pair of virtual twin GE's, 1600 series, that aren't heating.
All else appears to be normal. I've replaced the HV diodes with no
luck.

After discharging, all resistance checks appear to be normal.

HV side 70 ohms, primary 1, open to chassis.

Filament, 1, open to chassis.

Cap is hard to measure. I have a cheapie analog meter that only does
x1000, I get a very slight needle deflection when across the cap
terminals followed by an immediate return to open. My digital meter
has a very slow response time. I see it changing scales from M to K
but by the time it shows a number it is back to M (the internal
resistor of the cap). Both terminals open to cap case.

When running there is a slight to moderate hum. An inductive voltage
tester shows lots of power on the HV xformer, and it cycles with the
power relay when set to 100% on. The hum cycles with the voltage
presence.

I'd guess either cap or magnetron, any suggestions? On one of the
units, the HV diode was shorted (nothing visible) while as the other
one did not test as shorted.

I'd go with magnetron or bad filament connections but I assume you checked
those. The HV transformer wouldn't fail in a way that didn't result in
smoke or blown fuses. The cap is more likely to short than open and
you do get some response on your DMM. You could compare it to a normal
1 uF capacitor.

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