Morris,
You asked about replacement TO-3 transistors in the power supply. I have found BUX48A to work well. The originals I have tested have a too low hfe. The hfe too low made the supplies I worked on take longer to start up even after putting in new low ESR caps. In two pieces I worked on three were hfe of 2 and the other was 1. I know the circuit is set for a gain of 4. Using higher hfe is not a problem. The hfe is not too high in these. You will find them to be 15-35 hfe. The voltage rating of the A version is 1000V. If get a quantity of these, use the ones that are closest in percentage hfe. Gains of 22 and 25 are wider in percentage than 26 and 29 even though the gain difference is three in this example. Put in new good compound. I have MX-4 so that is what I used. Use what you have/want.
What Karin said in another post was great advice about the damper diodes across the power oscillator transistors in the power supplies. Something like MUR series in 600/800/1000V is a good choice. It may be a good idea to replace all the diodes around the two transistors with new/better spec ones. Her finding a higher speced TO-220 for some of the supplies, I thank her. I will order some as spares in case any of mine fail. Make sure the ceramic sleeve that goes in the mounting hole is not damaged. If the screw is too close or in contact with the tab to ground due to a damaged sleeve, it will blow a fuse.
Mark
