I’ve had a 70s integrated solid state amp - a Kenwood KA-5002 for a while now, and it’s started playibf awful noise in the left channel. I tried to bring it to a repair shop, but they just cleaned the pots and told me it was fine. It seems like the noise is intermittent, and when the unit is first plugged in, it sometimes works perfectly for hours before an issue. I’ve tested everything I can think of to no avail. The noise is always on the left channel, and isn’t affected by volume. It plays through the headphone jack, and both A and B speaker sets. Changing the input does nothing (as does frantically hitting every button and switch). Recently the static sound has brought what sounds like random power cuts. I really like the sound of this stereo through my bookshelf speakers and my headphones, and it looks so great in my living room. I would really like to get it running again, but troubleshooting the electronics is a bit above my pay grade. Does anyone have any advice? Maybe have a clue what might be causing this sound?