Tube experts! - I need your assistance.

I don't like tubes. My experience with tubes is *very limited*. I have had a few crash courses over the past few years...... Okay, I bought the Tek RM503 for my PDP-8/S. When I turned it on I heard some terrible noises and found the power supply voltages were all over the place (way off , like 10V was 500 etc..). This scope uses a primary transformer to supply the 6.3V to most of the tubes and has a separate winding for 6.3V for the CRT heater. Off this transformer another winding fed to a voltage doubler and then to an oscillator with another transformer to create a wide range of voltages. (12V to -3000). Picture this... the -3000 volts is fed right into the CRT heater (which happens to be directly coupled with the primary transformer). I have been able to locate the problem somewhat. If I remove the -3000 volt line between the HV rectifier tube and the CRT itself then the scope works fine! All waveforms are proper and the power supply works great (no picture of course). It can be a few things... I am hoping someone here who use to work on tube units might be able to tell me which problem below it most likely is: #1) A bad HV rectifier tube causing the HV to come back to the second transformer which would put a few thousand volts back into the secondary winding taps causing high voltage everywhere. #2) Bad insulation on the primary transformer secondary "crt heater" winding which jumps over to the other winding that happens to be the main powersupply winding (125V X 2) #3) The -3000 volt wire is closely tied to the other low voltage wires. Is insulation breakdown possible due to a crack? My next step will be to take a reading on the primary transformer (first transformer, secondary winding [doubled winding]) and see if thousands of volts are there... That might help determine if there is an insulation breakdown but from what I can tell when the -3000V is hooked up every voltage goes crazy. I am going to bed.. Hopefully I wake up to a great answer ;-) john PDP-8 and other rare mini computers http://www.pdp8.com