So last night at a show right before our last song, my amp cuts out.. so I freak out a little bit, but while the other guitarist is playing the interlude part I figure out my clean channel is still working. Crunch and Lead wouldn't make any sound. So I quickly put a distortion on my Tonelab through the clean channel and I'm able to finish our set.

Anyway, I think I need a new preamp tube since the clean channel is working and the others aren't? I'm not completely sure. I tested out my amp just now, and everything seemed fine. I was playing about 5 minutes on the crunch channel and then the volume went down a little bit. Not a lot, but enough to make quite a difference. The power tubes look fine.

I'm pretty used to how loud my amp should sound at the levels I normally play at, and the clean channel sounds like everything is fine. The crunch and lead channels on the other hand are definitely quieter than they should be, but they seem to be working again... for right now.

Also, our show was about a 4 hour drive away so I'm not sure if something got loose, but I would think if that happened my amp wouldn't have working at all last night...

So if anyone has any ideas as to what's going on, I'd be glad to hear them.
I have a huge fear if rays.
What you've described sounds like it may both a power tube issue and a preamp tube issue. Loss in power is def indicative of impending power tube failure. Post in the XXX/JSX/Ultra thread if you need suggestions or more help. So all channels work now?

When you change power tubes it is often recommended that you also change the last preamp tube as well. Also known as a Phase Inverter (P.I.) slot. Probably V4 if you have 4 preamp tubes. Also, for a trip like that I would consider taking all the tubes out while traveling or at least make sure they are all seated properly before you turn it on. Ususally however, if you have a tube that is not seated correctly one or all of them will get abnormally bright (orange) so if that happens don't leave it on like that or you will fry something.

Sorry for the wall of text, but I hope that helps. I'm not an amp tech so...
Well on the clean channel the volume levels seem perfectly fine, while the other channels worked the next day but at a lower volume than usual. Which is why I'm a little confused as to what's going on. Not that I really know much about tube amps... I'll check to see the tubes are all in good once I get home.
I have a huge fear if rays.