Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Hi,
I have found this forum and maybe someone can help me to solve a volume problem on my Crate Flexwave 120 head :

first, how it failed : I was pushing the volume (too high of course), and suddenly, it switched itself off and blew the power fuse...
so first, I replaced the fuse and it stayed on (light on the power switch, and integrated tuner), but I only had had a big buzz on the cabinet, absolutely no guitar sound at all.
so, I decided to search for the schematics, whitch I found pretty easily, and asked an IA, (don't laugh, it's always better than no help at all), to help me decode the schematics and guide me to test and replace what was blowed by the same references, and, finally, I got rid of the buzz and now,I've got a really nice guitar sound.

BUT

the volume is way lower than before, maybe half the volume, the IA tells me that there is a Bias problem but I don't understand where to search and here I am on this forum.

at this time I have replaced :
the Transistors :
- 2 TIP147 (Q15/Q23)
- 2 TIP142 (Q5/Q11)
- 1 2N5088 (Q9)
- 4 2N5087 (Q14/Q18/Q20)
- 1 MPS-A06 (Q12)
- 1 MJE-340 (Q19)

the "power resistors"
- 4 47/5W (R23/R33/R83/R85)
- 1 (R104)
- 1 (R96)
- 1 (R95)

the "classic resistor"
- 1 (R63) that was "brownish"

the "Filter capacitors"
- (C67) and (C70)

the "Diod Bridge"
- (D35)

I tested all the Diods with one leg desoldered from the PCB and all are OK, I cleaned all solders and tested if any contact was OK and with no contact with any other components or nearby solder...

(https://i68.servimg.com/u/f68/16/96/62/17/crate_10.png) (https://servimg.com/view/16966217/904)

the only thing i can see is this : on the power resistors when I mesure the voltage :
- on the R23 I have 2.5mv
- on the R33 I have 2.5mv
which seems to be OK, BUT I have :
- 3.7mv on the R85
- 1.4mv on the R83
and it seems that the problem is here...

so, please tell me that someone understand this schematic and maybe help me to solve this problem

regards

David