Hi all,
OK PROBLEM SOLVED!!!
YEEESSSSSSS!!!
After years of investigation, questions, etc. I met a guy here in France and in my town (Nantes) who repairs guitar amps, in fact he was a friend of mine years ago and we losted ourselves until all those years. Recently, in decembre, we met us in a music store in Nantes and we began discussing of what we did all thoses years, so he began to say that one of our friends is now reparing tube amps, preamp, etc... So I talked about the issue on my MP2 and he accepted to see what he could do.
After 2 months of investigation and test, he finally solved the problem, so he changed ALL the transistors and diodes on the compressor circuit and now my MP2 is sounding like the first day!!! He said me that the initial transistors were not good quality so this was the source of the problem and very difficult to see.
Here is his site for people who wants to contact him : http://pms.elec.free.fr/topic/index.html
YEESSSSSSS!!!!!
Cheachwood