Um, the HGM 5 magnets are a series parallel combination in series with the filter cap, they do NOT run across the dc line like a normal "wet" argon magnet. I dont understand if you have this configuration or not. If misswired they would pull things down to 100V or so. in other words magnet current IS the tube current..
Something sounds wrong here.. Are you sure you have a demand signal to the control card? With no analog demand signal it will either shoot up to the max limit or set there and flash. But not both.
Have you replaced the 14 or so volt zener that switches the supply from linear to digital mode?
This is NOT a true PWM supply, HGMs switch in mid stream from linear to pwm by sensing collector voltage on the passbank, even on a model 5. Not respecting that Zener's decision making function WILL result in making silicon monoxide smoke with a touch of metal vapor thrown in.
There ARE more then 2 wires to the passbank, there are considerable feedback signals in the system.
Steve
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