Just joined the XXX club! but there's a problem.

[Ravenous Enemy]

I just bought a secondhand peavey triple XXX via ebay. Got it home and tested in through a marshall 4x12, and there's a definite 'click' noise when i change from ultra to crunch with the footswitch. It's quite loud and i don't think i could live with it. Is this a known issue? Is there something wrong with it? What might it be?
I tried switching channels on the front of the amp with the footswitch disconnected, and out of about a dozen times of switching channel it make the 'click' once, so that makes me think it can't just be a dodgy switch on the footswitch.
anyay, if anyone has any ideas, they'd be received with great appreciation! if you think i should take it back to the guy, say so too!
cheers.

 

[ahjteam]

Where does the click come from? The speaker (elec/wire problem) or the head (mech problem)?

 

[Ravenous Enemy]

you can hear the click getting amplified through the cab. i'm guessing, because i could still hear the click once when switching with the switch on the amp face, that it must be coming from in the head; so yeah some kind of mech problem in there, i'm not sure.

to others with XXXs - has this happened to any of you?

there are a few mentions of it on tinternet, some suggestion of using different types of footswitch to remedy it. the previous owner says it never happened for him!

 

[Ravenous Enemy]

it just fixed itself! (Y)