Makes clicks?
One of the things I personally hate about the Fender imitation of a Model T, is that it has more circuitry dedicated to it's switching functions than it does to producing sounds.
You may have a problem in the switching circuit. One or more relays could be going bad, maybe explaining the clicks. I'm not about to trace all of the possible combinations through, but it is possible that could be the cause of some of your squealing and hum problems - for example, a relay staying open when it should be closed.
If this is the case, then you are better off taking it to a professional - and one that isn't going to cover up a problem by sticking incorrect tubes in the amp.
Play around with the Club/Arena switch - are the problems happening in only one setting, or do they happen in both. I'm suspecting a possibly bad switch here.