Hello all, I'm sorry if this is a duplicate post from elsewhere but I was wondering if anyone else had some tips for me on troubleshooting my amp issue. I have a marshall jcm 2000 dsl 100 with 1960A cab and just recently it has started crackling and the sound is not as loud as usual. So far the things I have done are: Replaced all pre amp tubes Chopsticked power amp tubes Applied contact cleaner to all tube sockets and also all jack connections and left overnight plugged in Tried multiple different leads Tried multiple different guitars When I plug the guitar into to return on the effects loop, the crackling and static completely disappear. Is there anything else I am missing here? I haven't replaced the power tubes as they don't appear to have anything wrong with them and to be honest, I've never heard what a bad one sounds like. I have made a couple of videos of this issue if you don't mind having a look. Thanks in advance.