Moving ahead, here's the parts list for the rebuild of both channels...though I will probably fix the left one first and then evaluate the situation:
Pre-Drivers (Power Output PCB)
#132-148 x 2, Mouser #610-CEN-U57
#132-149 x 2, Mouser #610-CEN-U07
Note: These are Centronics U57 and U07, as per other threads on the topic. Dunno if there's yet a better replacement.
Drivers:
PNP, #132-151: MJ15025G x 2, Mouser #863-MJ15025G
NPN, #132-152: MJ15024G x 2, Mouser #863-MJ15024G
Outputs:
NPN, #132-164: MJ15003G x 4, Mouser #863-MJ15003G
PNP, #132-165: MJ15004G x 4, Mouser #863-MJ15004G
Emitter Resistors:
.15 Ohm/5W, #139-105 x 8, Mouser #588-15FR150E
Note: This is an Ohmite 10 Series non-inductive part, 1% tolerance.
Diodes:
#070-031 x 4, Mouser 625-1N5394-E3/54
Note: This is a Vishay 1.5A/300V rectifier. If there's a better replacement, please let me know
I'll also replace the two 12 Ohm/.5W resistors with metal film 1% parts.
Anything else? Anything out of place?