Ok, I did a search, read all the pertinent info but nothing really took care of this for me. I'm basically trying to create a little online manual for what can be done at home by anyone with some time and a few bucks, and what can't. For example, where can I buy contact cleaner and what is the best way to use it? Do I spray it into the tube sockets or do I spray the tube contacts or am I dead wrong? I'm retubing with a full complement of JJ's, as opposed to the motley assortment of pre and poweramp tubes GC had in the thing. The manager said one of the preamp tube sockets has to be replaced and the crackling will disappear, forgot to add it's been crackling and I knew that going in, but I'd like to try cleaning it up myself before I pay some yahoo who may or may not know dick about my amp start poking around in it for 80 bucks an hour. So what can any tube amp owner do to their amp as preventive maintenance to avoid labor charges? I own a Mesa/Boogie 400+ specifically, thanks everyone. Hopefully this thread could get big enough to be truly useful to a lot of us who don't know as much as we'd like to but love the tube tone.