No reverb on my Crate V16. It's a little 9" Belton unit. I took it off and all the wires inside the unit seem fine, no loose ones. The proper cables are plugged into the proper jacks in the unit itself. No scratching from the reverb pot on top. Are there some continuity tests I should do without opening up the chassis? I'm out of my league there, but I'll happily put a continuity tester to anything in the tank or in the back of the amp that I can reach, if there's a chance it'll discover something. Or should I just take it to my tech?