2555 Silver Jubilee treble issue

[OSMOSE]

Hello

I have a 2555 Silver Jubilee in pristine clean condition that I've owned since 2003. Filter caps have been changed for JJs by a reliable tech a while ago, every buttons and pots work smoothly, it's been well taken care of. I've played it extensively for 5 years with a Dr. Z Airbrake attenuator, then it's been sleeping in it's flycase because I was unable to play loud enough anymore. I recently got into a loud band again and just started using it again, never being able to feel satisfied by what I was hearing anymore... so trebly, bright and harsh. I first got rid of the attenuator because I was just sick of it sucking the sound and I can play very loud so let it be... I play 100w mode clean channel, input gain and master volume are about 8 each. I set my presence at 2.5 bass on 10 mids around 5 and treble... 0 and I would go -10 if I could no kidding...
The amp has always been bright but it's become unusable really, I can't remember it being this unplayable, I wonder how could I ever have plugged a wah into it, I can't get anything out of it anymore, fuzz and distorsion pedals suck badly, it's just awful. The bass is tight as ever, mids are nice, but what's up with the treble I have no idea. I've never been higher than 2-3 and I know that's the setting John Frusciante uses so I've never been scared of playing that low, but I'm not getting anywhere now. I still play the same cab as I used to, standard 1960A, and I tried others with the same issue.

Any idea where that might come from and how to get this problem fixed? I've pondered clipping the bright cap but geez... will that even be enough, and I play loud so will it make any difference anyways... when I hear that some set their treble on 6-7 I guess something's wrong with mine... :?

Thanks for your help.

Much love
OSMOSE

[shooter]

Probably the best starting place would be your amp tech that did the cap job.  If your qualified, confident, rebuild your tone stack to whatever "darker" amp tone your looking for.

[OSMOSE]

Thanks, yeah I contacted the guy, I hoped I could avoid paying him a visit because it's pretty far away but I guess I'm in for a trip there... anything I've done so far was putting fresh tube and rebias, it has not brought result and that's nearly about how qualified I am electronically speaking. It used to bring good tone though so I hope some component simply went wrong and it doesn't require too much rebuilding, as of now it's basically unplayable.