Ok, the amp wants CBE then, so the parts are correct type.  If that is true then voltages for T5 in post #42 are impossible. 
The highest voltage for T5 should be at the emitter.
If it's easier for you to call them out as pin 1,2, and 3, that will work as well.
Recheck T5,T4, T6.

Sounds good.  Try it with load.  Some amps have trouble starting up loaded while on the bulb limiter.
If you get a bright bulb when you power it up loaded, you will have to power down, remove load, and power up.  Then (if bulb dim again) connect the load while amp is running.

Thank you! Things are looking much better!

Replaced Q4, insulated Q9.
Shorted input
No Load
Variac at full AC voltage 120VAC
1.03VDC across R97
0.29VDC at output

Is there anything else I should check before testing again with the 8ohm load?

Quote from: saturated on May 05, 2024, 11:10:45 PMAnyhow I found that if you are playing a song off YouTube on your phone like trying to learn it while you play...if you hold it up to your pickups it will play through your amp

     

I might need to try this...

T3 pin 1 goes to C4
T3 pin 3 goes to R7
So that checks out as well. It would sure be handy if Marshall gave us some voltages and a board layout.

D4 cathode goes to pin 2 of T5
R42 goes to pin 3 of T5
That checks out according to the schematic.

Yes, any transistors without plastic backs that are mounted on the heatsink need an insulator.
If the Q9 collector was in contact with the heatsink (ground), that probably explains the excess current through Q4 (via R97).

The heatsink is a large aluminum fin style with Q7, Q8, and Q9 attached. When I received the amplifier for repair it had what looked like white lithium grease between the transistors and the heatsink and no mica insulators. I cleaned and replaced the grease with Arctic MX-6 Thermal Compound when I replaced the transistors. Could that be the problem? Does Q9 need to be isolated?
Small update: The version of the Q9 D600K that I used has a metal backplate that is connected to pin-2 the Collector (the original did not have an exposed backplate). I'm going to make an insulating wafer and will update soon.

Quote from: Jesse on May 07, 2024, 04:01:33 PMQ9 has fresh thermal paste and seems to be tight to the heatsink.

What about it's insulator?  Don't it and the output transistors that are mounted on the heatsink have mica insulators or similar?

ah!, you are correct, I swapped R97 and R98 while typing.
Q9 has fresh thermal paste and seems to be tight to the heatsink.