M100 pedals cutting off

[bourniplus]

Hello everyone,
The sound of the pedals on my M100 sometimes goes away, either partially or completely. I've cleaned the tubes and re-tensionned the sockets. Tapping on the preamp makes the problem come and go. "Knocking the expression pedal at the end of its travel does the same. Any suggestion for how to troubleshoot this?
thanks in advance,
Martin

[bourniplus]

Well, it seems that the problem was a faulty 6BA6. I tried another 6BA6 I had and the problem went away. I tried the faulty 6BA6 in my M3 to make sure, and the pedals of the M3 worked normally but it seemed to cause crackle and pops. Does it make sense that this faulty tube could affect only the pedal signal in one organ, and then cause a different problem in another one?

[bourniplus]

I don't see an edit function, but it's actually 6AU6.