KRELL Mono Class A amp problem

Dear Audio experts

I have re-activated a pair of older (about 15 to 20 years old) mono Krell Class A amps.

Years ago I used them to drive Infinity RS-Ib speakers with no problems. Now I am driving a a temporary set of Anthony Gallos until I buy Revel Studios (assuming my wife's decorator approves).

Any way, when I turned them on, the power on light on one of them is green and on the other amp it is red.

Both play, but when asked to play rock at loud volumes, the one with the red light shuts down. When I lower the volume, it turns back on.

There is one fuse on each in the middle of the back and it seems to be all right.

When asked to play very loud, both shut down and the come back on when the volume is turned down

Any one have any ideas about what is wrong and how to fix it?

Thanks very much for your help.

(assuming my wife's decorator approves).

You might want to look at getting into a new hobby. Maybe macramé or needlepoint, providing your wife's decorator will approve of course. Or, maybe just shoot yourself in the head. (That's a joke, I say, that's a joke, son)
Probably the BIAS has gone off due to capacitors and such.
The red one the bias is probably far enough off the make it self warn you.

I would find a GOOD serviceman to replace the power supply caps, and check any others, and re-bias the amplifiers.
The main thing IMO is the bias is getting off spec. It can drift over time, and Class "A" amps need it to be pretty 'tight' to specs.
This is only my opinion.
The fact they work, is a good indication i am on target.
Usually with old Krell amps the caps go bad and in this case it sounds like the relay/protection circuit. Sooner or later the other amp will do the same thing. I would suggest calling Krell to find out how much it will cost to recap both amps, that way you can decide if you want to get them fixed or not.
When amplifiers have not been used for a while it is a good idea to start them up slowly by using a variac.
It USE to be Krell's policy on mono amps that they had to have BOTH of them to work on when one went bad. The freight was quite expensive; I had to return a pair of KMA 100s twice in a year or so. I would look for a good local repair place but this is not easy [gross understatement]. If you put your location on here perhaps someone on here can suggest a good one.