My 11 year old F1X is sick. The output level has dropped drastically, and in order to compensate, I have to turn the volume up a bunch, which causes a lot of distortion. This is worse with the 18v Modulus than with the low-output DeArmond, so I was thinking the tube was dying. Tried 3 different tubes, same thing. It is worse if I plug into the effects loop return, but then again, it's a little louder, too. I was able to finish a show the other night with the DeArmond, but not the Modulus. I will be calling Alembic Monday, but until then, any suggestions?