About 15 years ago I had bought a Peavey tube amp on ebay and the power section was buzzing. Everything I read online was that it needed new filter caps, even though the amp was about ten years old.
I took it to some hipster late-20 early 30 that was operating out of the back of an inner city studio. He plugged it in and said "this is normal, its a high gain amp, they all do this". I was out the $75 bench fee.
Not to be deterred, I called peavey and ordered all the filter caps. I did the work myself and the amp was whisper quiet.
That amp "tech" was an absolute clown. If he can't diagnose and replace filter caps, wth was he doing in business as an amp tech??
It blows my mind how people can set up shop doing something and have no idea what they are doing.