Stage 60 OD1 issue

[peege]

Hi all, long time lurker, first post.

First off, thanks to all who have gone before me to post problems and then solutions.

Now my issue: my OD1 channel stops working (tone changes) after about 30-45 minutes of being on. The light goes out and if I switch to clean or OD2 (using the selectors on the face of the amp) then I can not select OD1 again. If I stay on OD1 it still produces sound but, as I said, the tone changes. When using the footswitch I can cycle through each channel but OD1 tone is still “different”. In each case the light indication OD1 selected (on the face of the amp) will not light up. When the OD1 light goes out, and changes tone, the voicing switch has no effect.

What I’ve tried so far: re-tubed, power and pre amp.
Swapped tubes in V2 and V3 (I’m pretty sure. The two tubes furthest from the power tubes).
Re-seated all the tubes after replacing

Sorry for the long post. Any help would be great. I feel like it’s a degrading diode, or an “and/or” gate but as stated several time in the forum the schematics are rarer than unobtainium.

Thanks for looking

[peege]

Update-it was caused by loose solder joints on PCB.

I was hoping to solve the issue myself, hence the post here but due to the fact that the schematics are not available I had to take it to the shop. Originally the shop told me that it was an 8 week lead time and I had gigs booked so I was hesitant to take it in. They turned it out in 10 days so all was good. The clerk couldn't tell me which ones had come loose(he didn't know) and also he couldn't say if other ones would come loose over time. I guess I'll wait and see.