Are reverb and channel volume connected?

[mkVplayer]

I was playing a gig Saturday night and half way through the night it seemed like my 2nd channel was ridiculously quiet. Later on I noticed that with the reverb off the 1st channel too was really quiet. If I kicked on the footswitch reverb on either of the channels the volume was back as expected.

Does this sound like some sort of tube issue, or something bad in the footswitch? Other?

 

[jmontgomery]

I'm betting on the reverb driver tube.

 

[mkVplayer]

I'm betting on the reverb driver tube.

Looking at the manual it seems like that would be V4? Does the front panel come off for easy access to the 12ax7s? If not, any tips on how to get at it? There's a cage around the power tubes which I guess must snap out somehow. Is it easier just to pull the chassis from the cab?
Mine's a head.

 

[jmontgomery]

You have to go at it from the back. V1 is the only one that's a bear to get to. The cage comes off easily and you may have to pull the power tubes to make it easy. You shouldn't have to much trouble.

 

[mkVplayer]

Is there any way to test this - switching the reverb on and off - without the big foot switch? I left it in the trailer with the pedal board stuff. Naturally.