Vintage amp restoration and Beyond

[GoldenVulture]

The squealing at high volume has slowly disappeared almost entirely.
I'm wondering whether one of the KT88's isn't up to scratch. After a while sometimes, one particular one of them will start redplating. I changed it's position twice but it's still doing it some times. I might have to get another one to replace it. This amp is running pretty close to maximum voltages for the KT's.

V1 which was squealing is almost squeal free. I discovered it squeals like a pig if you don't have a cover on it.

I finally nailed my red plating and my stupidity. I thought the bias voltages it was running seemed a bit low. I should've thought of this sooner
 As there were no reference voltages on the circuit I've been using, I checked what my other amp that runs KT88's is biased at. Yes they were too low. The higher the plate voltages the higher the bias needed. As the Power Supply is a hack of two circuits I had to modify it again by changing a couple of feed resistors. That put the bias into a usable range. No more red plating.
 At the current time I'm running it at - 42 Volts. I tried it at - 46 Volts for a while, I might go back to it. I'm looking for the bias sweet spot. The 88 data sheet suggests bias voltages in the - 40 and - 50 volt range depending on your circuit confiuration. This circuit seems to work in the 40 volt range.

Looking at some of my pics of the power supply I noticed another wiring mistake. None the less it has been rectified.