Carvin R1000 power amp problem

[Nickodemus]

I have an R1000 Rev H which has been losing most of it's volume after about an hour or so off live playing. It just fades out slowly. Both amps are dropping eventually to zero volume. Its NOT an on/off situation they drop gradually. didn't hear any distortion so I don't think its a signal path issue.When playing live typically vol is 6-7 bi-amped into a 410 xlt and 1-15 each at 8 ohms. If I shut it off for a break (15 mins) then power up, sometimes it works for a while then repeats the problem. sometimes I still have no vol. Last gig, I accidentally sound checked with wireless transmitter off, so it got a loud blast of static at the beginning of the night. That night, the problem started immediately after that. It didn't need to wait for it to warm up. Line out to mains works fine. Effects still come through mains from line out when it's acting up, so I don't think it's a problem with effects loop jacks.tried it in line and direct position. same results.
I'm thinking it is shutting the gain down through the op amps due to a thermal issue or over current. Can anyone give me any tips on how to troubleshoot this. If anyone has any experience with these symptoms on this amp, I would greatly appreciate any insight.
I do have -.4 vdc on both speaker outs and when I switch it to bridged it drops to -.1 vdc
output transistors are getting hot with nothing running through it and no speakers connected. fan runs all the time. I don't know if it's supposed to. when I disconnect the +/- 15v supply (driver section) the dc on the outputs drops to zero.
I have years of experience repairing amps when I was a kid, so I'm going to do the repairs myself, but I've been out of the loop on repairs for a couple decades and am a little out of practice so any tips would be GREATLY appreciated
I need this thing for a gig next Sat so I'm getting a little antsy

[Jazz P Bass]

Well. here is the schematic.

[Gtr_tech]

.4vdc is too much offset for that amp. I recently had one similar thru here (R600) and there was barely a few mv of offset at the outputs. That makes me think it could be anything from the diff amp on thru the driver section. But....since the offset (and faulty operation) is common to both channels, I'd look to the pwr supply first. Verify the operation of the 15v rails, and closely check the connectors on the ribbon cables from the PSU board. The one I had thru here had intermittant problems that I tracked down to one of those connectors. I just eliminated it altogether and soldered the cable to the board.

Be advised that these are *full* of SMT caps that are reaching end of life. I replaced every damn one of them after I found a few that were bulging. Amp sounded a shit ton better after this. I used thru hole parts to avoid the same situation down the road.