Carvin DCM200L volume fade

[rnolan]

So my Carvin DCM200L has a volume drop from time to time, then comes good again.  It's in my live rig so this is more than just an irritating problem.  Any ideas guys?  It has a push in eq button (like a loudness button for low volume eq correction) on the front which I toggled the other day (never used it before) and, interestingly, has seemed ok since but I'm not sure.  I do know that these sort of push in/out buttons on the back of the MP-2 can cause issues from time to time.

[MarshallJMP]

A loudness button shouldn't give a volume drop, I think it give a sort of tone difference.
Volume drops can be caused by a lot of things, tubes, pots ,jacks would be the first too look at.

[rnolan]

The eq button reduces the mids, but wouldn't normally cause such a large volume drop.  But it affects both channels which is why I wonder that, if it's a bit gummed up, could it be impeding the signal flow?  The drop is even in both channels.  So no tubes, its a solid state switching power supply amp.  Maybe it's an intermittent issue with the power supply?  It's always fine for 10 or 20 minutes, then kind of halves in volume, the 5 to 10 mins later comes back.  Pots and connectors are fine and also it's both channels evenly.