Problem with loop master?

[blitzie]

Okay, everyone. I have a problem.

I gave my 2010 Nitro to an amp tech to get it re-tubed. He did a change-over for me to KT88's from EL34's.
Before I gave it to him, what I did was jack up the volume on the front of the amp, and then adjust the volume to taste on the loop master on the back of the amp. Seemed like it would act as an attenuator.

Anyway, I got it back and now my loop master doesn't work. For whatever reason, it just doesn't do anything. I've tried it on full power and half power.

Any ideas?

[Tempest]

Has your nitro got a loop bypass switch? Mine has no loop master on it, but you can bypass the whole loop. It could be that it's some how gotten stuck in the full bypass mode, ask your tech what he did...