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Built the Tramp from a kit. Finished it just over a week ago. Worked fine right away. I have used it perhaps 6 to 8 hours total. Using the JJ 6V6 and 12AX7 that came with the kit.
Wired the impedence switch for the 6 settings (3 for 2.5K and 3 for 5K). Using the Tramp with a Mesa 1x12 8ohm cabinet.
Yesterday hooked up a second speaker cable and ran it to the 2x10's (total 4ohms) in my Blackface Vibrolux Reverb. Left the Mesa attached. Figuring the total load on the Tramp would be around 6ohms, I left the impedence switch on 8ohms. This setup worked with no issues, and sounded extremely good. Used it for about an hour like this, then disconnected the Vibrolux speakers and went back to running with just the Mesa cab. No problems.

Today's a different story.
Powered the Tramp up, everything seems normal. Plugged in guitar, set Power on max, Master volume on max, Volume on 5. No sound. Turned Volume to max...very, very faint sound, accompanied by some hiss. Like a really low level signal was coming in.
Started investigating. Turned the Tramp off and verified the guitar and cable going into another amp was good. Tried the Tramp again, going into the Vibrolux speakers without the Mesa connected. Same result--output from Tramp is almost non-existant. Am now starting to worry.

Took the Tramp out of its cabinet (it's a head version) and looked for any obvious issues. Nothing has changed since the kit was completed. No loose/broken/suspect connections, no ground on shielded cable touching anything it shoudn't, no bad smells, no scorch marks, nothing appears wrong anywhere.

The only other tubes I have are in the Vibrolux, so I guess I could use one of its 6L6's in the Tramp to rule out problems with the 6V6. Could also do the same with a 12AX7.

One thing that struck me as strange has to do with the impedence switch. As mentioned above, I did the mod to accommodate the 2.5K/5K settings. The switch came in the kit set for 6 positions, so I didn't change that. Wired it per Snowy's pictures/diagrams posted earlier on this forum. To use my 8ohm speaker and 6V6 tube, I set the switch on the second-from-left-most position. What's odd is that the switch, starting from the left-most position, actually moves 11 clicks around (clockwise) when I would have expected only 5 clicks. No idea if this is right or wrong, but my setting on the switch did not change from yesterday (when everything worked OK) to today.

Suggestions?
Swap tubes?
I have a digital multimeter, but because of all the warning messages in the kit instructions, I'm not terribly comfortable taking voltage measurements. Having said that, I AM willing to take those measurements if I have exact details on how to do it.
Thanks for all help offered. Am attaching a couple of pix taken at kit completion time in case somebody spots something terribly wrong. It is unchanged today.

OK, fixed.
Decided to go ahead with the tube swaps, one at a time.
6L6 in.....still had problem.
Different 12AX7 in....problem fixed.
Left the 6L6 in there (it's a Ruby). A bit darker sounding than the JJ 6V6, but quite a bit more headroom.
Apologies for wasting your time.

Sorry about the tube. Infant morality. It happens. But You should learn how to do voltage measurements when it's working!

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Weirdness going on here.
Left the 6L6 and replacement 12AX7 in the Tramp, went away on business for three days, came back, powered up, and same deal. No sound. Well, that's not quite right. It hummed, but absolutely no signal was getting through. The 12AX7 was obviously getting juice (filaments glowing) but the 6L6 was completely dark, and cold to the touch.
Powered down, swapped the JJ 6V6 back in....no change.
Powered down, swapped the 6L6 back in...no change.
Powered down, removed the 6L6 and very carefully reinstalled it, making sure it was seated down into the socket as far as possible (but really, no different from any other time I had installed a tube).
This time it worked fine. I've had the Tramp powered off and on a few times during the course of the day, and it's still OK. Fingers crossed.
This seems to be a slightly different type of failure from the first one I reported, but still related to either tubes or tube sockets. Both sockets, but especially the 12AX7 one, have EXTREMELY tight fit for the tube pins, so it's hard to imagine one or more of the pins was not making good contact.
I am waiting for delivery on a Tung-Sol 12AX7 and a Winged-C 6L6 so my tube-swapping adventures are not over yet.
Hope I can get to the bottom of this soon.

By the way, here's what it looks like on a fine September morning. I put an extra bit of ornamentation on the cabinet just to make it one-of-a-kind.

Nice looking rig. Check your guitar cables and speaker cables and connections. Or maybe a loose connection inside somewhere.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Update....
Got the Winged-C and Tung-Sol tubes installed. No sound.
Started swapping tubes around. On about the fourth swap it started working again. I even swapped back in the JJ 12AX7 I had previously thought was bad. Worked fine.
Figured this can't be just tubes, and took the amp out of the cabinet (again).
Pored over every connection, paying particular attention to the tube sockets.
Could find absolutely no fault with the octal socket connections.
But while checking the 9-pin socket (part of which is hidden by the corner of the turret board), I spotted a problem.
On pin 6, which is one of the joints that gets soldered after the board is put in place, I had made a hook with the wire end, looped it through the hole in the socket pin, and soldered it. There's no way to get wire cutters in there to snip away any excess.
What I saw was the end of my 'hook' sticking up and almost touching the 330K resistor lead going to pin 7. I physically separated the connections to pins 6 and 7 as much as possible, simply by pushing them apart. And I eliminated the 'flying hook end' on pin 6. Powered up, everything's fine. Used it for a half hour or so, no problems.
Came back an hour later, powered up, all OK. That was about 10 this morning.
It's now 4:30 p.m. Powered up.....nothing. Just a bit of hum.
Discouraging.
Obviously I still have a problem, but I don't know what to look for. The guitar's OK, the cable's OK, the speaker cable's OK, the speaker's OK, the tubes are OK. Kinda points to a wiring error, doesn't it?
And to make things worse, we're leaving for a 10-day vacation trip tomorrow, so it will have to wait.

Yes, it should like an intermittent connection. Jumpers you can't see, or maybe a solder joint. Frustrating. You may have to touch up some joints.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Dr. Stephen was exactly right when he said 'solder joint'.
After several hours of troubleshooting, I found a terminal strip (lug #3 on the 'power ground' strip) which had 4 wires going to it. 3 of them were soldered OK, the fourth (underneath all the others) was crimped, but not soldered. And, of course, this was the wire going to one of the heater pins on the octal socket. Ergo intermittent juice to the tube. Ergo intermittent sound. Frustrating that it took me so long to find this, but in my own defence, this (un)soldered connection was just about impossible to see. I found it by getting oddball results when checking heater voltages across pins 2 and 7 on the octal socket.
But I'm happy to report that, after a quick re-solder of that connection, the Tramp is back to normal operation.
And with a Tung-Sol 12AX7 and a Winged-C 6L6, it sounds enormously better than with the JJ's. Well worth the additional investment.
My thanks to Stephen for helping me in the debugging, even on a Saturday. Much appreciated.

Learned a lot in this troubleshooting session I think!

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps