Sounds like that service center hired the technician that I let go. He was a recent tech school grad and they taught him that an ohmmeter was a gold standard transistor tester. He could not follow instructions on how to repair a power amplifier and many other things. He didn't read service bulletins. My recall rate was nearly zero. We had a number of units come back that he repaired. None of these would have come back if he had followed my instructions.

A couple years later we had a unit come in for repair with a note that an instructor at the above tech school said that I should replace a certain transistor to cure a noise issue. Er ... after a brief shot of Volume control cleaner the unit was fine.