Bias adjustment for the CARY SLI-80 Integrated Amp

To my fellow tube lovers: I have been here before, and I am back because I need help in solving an issue I have been having with my Cary SLI-80 Integrated Amp.
Very Simple: I cannot adjust the bias reading on the LEFT channel. After warm-up [about 10-15 minutes] I can set/reset the bias reading to 75-80 ma. Wait... there is more .... After about 30 minutes, with or without music, with the meter connected, one sees all of a sudden the needle jumping all over the place; talk about erratic readings: as low as 30 ma and then as high as 150 ma. When I try to adjust down the potentiometer, it gets to a point counterclockwise, where I can no longer adjust it, and it still reads a very erratic reading. If I adjust clockwise, the mamps start to go up even higher.
Either the outer-most power tube on the left gets RED HOT, or the power fuse blows. If I reverse the tubes [right to left and so on, one would think that the issue would be reversed, but it is NOT. Same erratic reading on the outer-most LEFT SIDE. SOMETHING IS WRONG IN THE WIRING INSIDE THE AMP. The problem is that the amp has been doing this now for quite some time and it has been sent back to Cary where they charge and tell me that nothing is wrong.

Where do I need help? Does one of you kind folk have a SCHEMATIC of the SLI-80 that I can get from you to see if I can track where the damage is? Or perhaps you’ve had a similar experience and knows where trhe problem lies. I really need help on this. Best to all and stay well during these trying times. Richard