Recommend repair tech in so Cal

This is my standard response when GM comes up...

"Suggest performing a deep Google on George Meyer before using them.

I’ve lived in the Los Angeles area since 1977."

DeKay

George Meyer is legit. I've had concerns resolved by them. 

The issue is if they can get the schematic.

May be a good idea to email Icon Audio about their authorized repair centers. Some companies will not release schematics to just any repair facility.

there are many

but george meyer av is a very good one

you can also try scott richardson - he works on older tube amps, see if he will look at yours