GM36 tube issue.

Hey guys, been awhile.

I'm having an issue with my GM36.
When I turn the amp on in STANDBY mode, my TSC lights read left to right: 1,2,4 light. 3 no light.
In Play mode, left to right: 1,3,4 no light. 2 light.
I figured inner tube set was bad. Original Chinese tubes. So, I just went ahead and ordered an all new full JJ kit from Eurotubes.
Swapped all the tubes out. Exact same problem. This is telling me that it's not the tubes. But, maybe something else in the circuit. Internal fuse possibly?
I haven't looked in by the circuit boards, yet.
I also, tried rolling all the paired tubes into sockets 2 and 3. No difference.
Any thoughts. Anyone had this issue?

How old is the unit? Did you register for the 3 year warranty?
http://hughes-and-kettner.com/support/warranty/
Try contacting via email if you are in the USA hk.usa@yorkville.com

I had a wierd code on my Coreblade that eventually wound up being a bad tube. I don't get why H&K had Tube Safety control but virtually know documentation on the weird codes that come up. Yorkville is linked to H&K and they will actually respond back to you. Note Yorkville didn't fix the issue till after I sent it in at a significant cost in shipping and repair was added on top.

I have seen cases where the TSC gave problem results.  A change of the valves did not change what the TSC reported so the assumption was made that there was an issue somewhere in the circuitry.  However, after a day or two the TSC then reported correctly with the changed valve setup.

It may be that the TSC takes time to recalibrate itself.  Try again after an overnight wait.  If that doesn't work then try turning the amp on, warming up, testing the TSC, then turning it off again a few times to see if that triggers the TSC to update to your new valves.

By this time that may have already happened of course.  If it has we'd appreciate you telling us as this is a newly identified wrinkle for us here.

Thanks guys for the suggestions.
I bought the amp used a couple years ago. I'm guessing the warranty isn't transferrable.
Bordonbert, I'll try your suggestion tonight when I get home.

Finally, got around to trying bordonbert's suggestion. No change. So, I try contacting yorkville and see what they suggest.