Boostchannel troubles

[MjS]

Hi, I bought a second hand H&K Tube 50 last year. Recently (2 months ago) I got the tubes replaced by JJ tubes (pre-amp tubes were still the original H&K ones, poweramp tubes were Tesla I believe). Sound improved quite a lot. Since a few weeks I have encountered a problem: channel 2B (overdrive+additional boost) is not working properly. It sounds weaker, with less bass and gain than channel 2A. It used to have more bass and gain! I think it might be because I boosted channel 2B with a boost-pedal which gives quite a lot of boost. I decided to change pre-amp tube 3 to the H&K original one (which was still working correctly). This improved nothing. Is it another pre-amp tube? Or is it another component failing? Could you tell me the functions of the 3 tubes? I tought tube 3 was for the boost but now I think I might be wrong. Also I encountered an empty opamp socket, near the input of the amp (14 pins). Is this normal? I mailed H&K about it...maybe you guys might have an idea?

And yes, this has to do with stompboxes. It was my own DIY boostpedal, which was not quite friendly on my amp  :lol: