One thing I should have been clearer about; when I said I have sound now on the previously dead channel, I meant via headphones... the outputs are still not playing dice. Previously before replacing the dead driver the headphone output was garbage too. No surprise.
I hadn't complained much about it earlier, but you might have noticed voltages on my diff pair bases/emitters and the source drain were about 0.2V higher than they should be. No matter how much I adjusted the VRs I couldn't get rid of it. Today I pulled the diff pair and while they both were working one of them had about half the gain of the other. So I replaced the two 2SA572 with KSA992 (which I spent some time on getting a nicely matched pair). TR601 tested okay. Now I can make the adjustment with VR601 and the voltages in that section look really good now! That is something I would have ended up coming back to clean up anyway, so I'm glad to have got that part sorted.
Then I tested TR604/605 (2SC1124). Both tested okay, but the legs of one of them broke off, so I replaced both with KSA2690A (not different pin-out).
I tested the TR606 yet again. I decided to replace it with a new KSC1845 even though it tests ok, since I've had bad experiences with the 2SC485 in my sansui units.
TR607/8 (2SC734/2SA561) tested okay and were reused. TR609/610 drivers are already new from the other days, and the output transistors are also new.
While matching up that diff pair helped out at the front of the circuit (and replacing TR610 the other day got rid of the weird -negative voltages all over the place), the issue I mentioned after replacing TR610 still exists. Take a look at the new voltage pic. For example you can see on TR606 I have several volts +ve more than I want on each pin. You will also see several of the bases downstream from are elevated by a few volts. I didn't note any voltages for the outputs or TP3/4 as they are all in the one or two mV range (or possibly open?).
So maybe I will check my traces around the output transistors tomorrow, but I still don't really see how that should cause those voltages at TR606 (?). Looking at for example the base of TR606, I actually have a reasonable value for 10 seconds, let's say somethinkg like a few hundred mV, and then it starts creeping up slowly to ~6V. (EDIT: also that 53V on the rail starts at 50V and creeps up over the same time scale) And when I say slowly, I mean it takes a minute to reach steady state. I feel like that time scale rules out a few things already. Thoughts??? If no suggestions I will focus on taking a few more voltage points around TR606 and try to find why the voltages there are so high.
Also note that these symptoms are the same from after I replaced TR610, to after I replaced the several other transistors.
(NOTE: TR604 runs hot, but that is the same on the good channel. Another note: R619 is still 60Ohm instead of 68Ohm due to previous tech work so that still needs to be fixed).