JCA 2112RC problem

[Dusty Boots]

Wow, I did not realize how long it had been since I'd been here.  Nice new digs HC, and I guess my old moniker got lost somewhere along the way too.  Anyway, the reason for my post.  I've been very busy with work this year and fired up my amp for the first time in months and months today and ran into an issue.  I struck one chord and not a half second after I hit it, the sound cut out and I couldn't hear anything.  I fiddled with the amp volume and with the volume at about 7 I could faintly hear sound again, and at max volume it was still below talking volume but still audible.  I turned the volume down again to half, played a chord and it cut in again for only a half second scaring the piss outa me.  After fiddling with different cables, other guitars, it never cut in again, and I could only faintly hear it at high volumes.  Now my limited knowledge has caused me to suspect a couple things.  I've had the amp for over two years now, I have never changed the stock tubes, but then again it hasn't seen heavy use.  So could it be tubes?  The fact that it cut out and in and out has me thinking it could be a connection issue somewhere, or potentiometer issue.  Before I rip the bad boy apart or take it to a tech, does anyone have any insight into what this problem may be?  Thanks fellas, and I apologize for the long winded post.