Any diagnosis for a Strange Blues Jr. Problem?

[Bluedano1]

Hey guys, My Blues Jr. which BTW I have had now for about 8-9 years and used on many gigs without any trouble other than an occasional tube change is exhibiting a weird problem that has NEVER happened, before this week:

The last 2 times I have played it just at home at moderate volume, the volume just disappears and fades to no sound in the middle of playing, for a quick moment, and then returns-did this a few times today and the same thing happened earlier in the week. Its like the amp powered down, then back up. The sound decays and returns...

Just a little info, this happened after the amp has been ON and played for about 1/2 hour or so; was using a Strat thru a Bad Monkey earlier in the week and Les Paul copy thru a Barber Direct Drive- just kind of trying out guitar/pedal combinations for upcoming gigs. I don't think it has been any kind of power surge from my home, as the amp's pilot light doesn't go out and the tubes look fine. The sound of the amp when the power/volume comes back is just fine- no change in tone or distortion. Any ideas?- I'm not an electronics guy but would love to hear some opinions- thanks!
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[kevinhifi]

The tubes may look fine, but that doesn't mean there isn't a problem with one of them. It could be a tube socket too.

[whiteop]

when the amp is cold and unplugged you can use some contact cleaner spray and pull the tubes and spray the tubes then work them in and out of the sockets several times to clean them out. I hear that this is sometimes a problem when the amps get older and haven't been serviced in awhile. Might be time for a tube change.

[bluesjunior]

I had a similar thing with mine a couple of years back and it was the 12AX7 in V1 was the problem. Try swapping the three of them about and see if it helps.

[Blue Strat]

Clean the sockets, as per above (sometimes even just removing and reinserting all the tubes can help) and try the amp with just your guitar and cable. In tracking down problems, especially intermittent ones, reducing the number of variables is crucial.

[Bluedano1]

Originally Posted by Blue Strat

Clean the sockets, as per above (sometimes even just removing and reinserting all the tubes can help) and try the amp with just your guitar and cable. In tracking down problems, especially intermittent ones, reducing the number of variables is crucial.

Hey Guys, thanks much for the tips. I will get to work on it asap today!

[Ronsonic]

That it fades and returns suggests a heater supply issue. Could be a preamp or driver tube or socket. If it happens often enough, you might hang out playing with the amp facing away so you can watch the tubes and see if one or all go dark.

Go with the clean and reseat drill others described. If it continues, suspect bad solders / connector in the heater supply. After nine years some time on the bench is probably due.

[Bluedano1]

Originally Posted by Blue Strat

Clean the sockets, as per above (sometimes even just removing and reinserting all the tubes can help) and try the amp with just your guitar and cable. In tracking down problems, especially intermittent ones, reducing the number of variables is crucial.

This is the one procedure I can handle!
I have some DE-Oxit contact cleaner and cleaned the tube pins and sockets.I plugged guitar directly into amp and noodled(just quietly) for over an hour- so far, so good. Has not cut out...