I have a bunch of System 1 PS that I am getting around to repair. One big pain with this PS is the +5VDC pass transistor. It uses the frame of the PS as a heatsink and it's leads protrude through the frame heatsink to the PCB Pads. It becomes a pain to unsolder, fix the PS and then resolder the pass transistor to the PCB. If the PS is still not working correctly, you have to desolder the pass transistor again and go through the whole process again.
What I did was the following.
First I drilled out the pass transistor's emitter and base Pads and a hole for the emitter wire.
Solder a wire to the emitter track area and a wire to the base track.
Then attach the PCB back onto the PS frame/ Insert the pass transistor through the frame and into the PCB. Next solder the emitter wire to the transistor emitter lead, then the base wire to the base lead.
Now you can more easily take the PS PCB apart from the pass transistor than the stock PS.
I know some folks will put the pass transistor on a separate heatsink. But then you have the heatsink hanging off the PS and needing to be mounted in the Head. But I use this method as everything stays self contained on the PS frame.
I also change all electrolytic and tantalum caps on the PCB, not just a couple as per Clay's guide. It's cheap enough and if your in there it's easy just to replace them all and not have to worry about any more.