Technics SA-410 ICQ Biasing, 1983, 45 Watts Per Channel STK Amp

OK, here I go again. Here’s the Technics SA-410 from 1983, 45 watts per channel. STK chip with the Technics New Class AA amp circuit and some fancy monitoring LED’s.
I had no idea an STK chip receiver like this had an amplifier adjustment. Technics calls this biasing “ICQ” or Idling Current Quality.
It’s one of the few that I’ve seen because all of the later generation STK receivers don’t have amplifier adjustments. At least, not many.
Anyways, I was expecting this to be over because it performed well, but it actually was under. So I made the adjustment as you’ll see in this video. And it’s now running at factory spec.
These STK chips are fragile, and I was reading how some people have blown them out by turning the ICQ bias up too much, so when I was adjusting and saw this bounce, I got a little worried.