"Trust your own troubeleshooting. "

I think that should be rule number one.

I was at one shop where when a tech got stumped on a unit he had to put it all back the way it was. I don't mean all the screws but electronically - remove jumpers and restore any disconnections used for testing. Then it goes to the next guy (usually me) and the other guy is told to shut up and not say a word unless and until I ask something. The idea here was to get a purely fresh perspective on the problem. It wasn't to the point of unreplacing parts, but make it so it doesn't go poof when you plug it in.

As for Sony, they were terrible up here 25 years ago. Sometimes we had to send them a thing or two and I noticed the bill was not honest. They didn't even want you to know what they did.

Sony is in the business of selling, not fixing and always has been. At least 25 years ago they had a quality product. Now the name means nothing. Well it does mean one thing - "The parts herein do not fit anything else and no other parts fit herein with the possible exception of those devices with three or less terminals".