Hey RobbHell,
I´m afraid this diagnostic work is beyond my technical capabilities.
MJMP appears to live in Belgium which would be quite a trip from here...
I guess the best would be to hand it over to the guy whom I let fix my tube gear, along with your hints and advice.
I bought the used MP1 15-20 years ago. Used it for a while (and I know for sure that V2 was working back then), and later had it sitting in my rack only for the chorus.
It must have been sitting around without being regularly used for about 10 years, even though I occasionally dug it out and toyed around with it a little - without doing much editing. So I can´t say for how long V2 has been disfunctional.
It´s version 2.01.
Then again, I am wondering if I am missing something important without the second gain stage, since V1 seems to give me way more gain than I´d ever actually need. (?)
Also take a look at the F wire. Could you tell us the history of this unit.