Here is a story that may be able to help someone else avoid frustration.
Last night, I set up for the nights gig with my trusty 13 month old TC15 again. Upon trying to do a sound check, I noticed the volume level was fluctuating up and down and I didnt know why. I suspected a bad tube, so I swapped all the preamp tubes, the two power tubes but it didnt help. It was happening on both inputs.
I took a look at my pedal board (all hard wired and I dont mess with it) and it appeared OK.
After farting with the amp again (and by this time wasting about an hour) trying various tubes, I lost all sound!
Now for some reason I thought - try plugging into the amp direct. I did, and suddenly I found I had my sound again.
At that point I went over my board again, and discovered one of the george L's plugs had worked its way out of the jack. Must have been making intermitent contact and then none at all.
I felt like a loser - but hopefully this may help someone else. Go over the cords first, then take the amp apart!
AJC