I saw that on post #11:
Collector of TR435 21v
Base of TR434 3.1v
Terminal L4 for the R/L meter lamps 0 v
but since you have a good voltage at the collector of TR435, it is possible that L1 and L4 are inverted on the schematic (vs the board). This week-end I will open my CA410 and I will check. If one lamp is bad, no light...
I did a mistake in my previous post where I asked to take the resistance between TP2 and the collector of TR425. I suggested to use the mounting screw but this screw is possibly insulated from the metal flange, which is the collector of the transistor.
Please, can you repeat the resistance measurement between the test points TP2 and TP4, and the collector of the power transistors?
When we have a large positive voltage at the output of the power transistors (like you have), there may be a few causes:
1) shorted C-E junction in the NPN power transistors (TR425), and/or NPN driver transistors (TR421). So, measure also the resistance between C and E of TR421, and TR422.
2) broken path on the base side of the PNP driver transistor, by a bad (open) voltage gain transistor TR411, or open resistors R461 or FR401. If one of these three components is bad, the base of TR421 becomes almost directly connected to the positive supply rail by R449 and R453 and both TR421 and TR425 become into saturation (low Vce).