Reverb Issue on my Boogie

[Ice Man]

I have a Mesa Boogie Subway Blues, which has a huge, great-sounding reverb tank, but the reverb seems to work fine above 50 %, but below 50%, it doesn't work at many of the positions on my reverb control/pot. If I tweak it just a bit from a position where it's not working, I can get it work, but it seems intermittant at best in the lower 50% of the reverb range.
Any ideas?
Thanks

[kmcguitars]

Re: Reverb Issue on my Boogie

I Imagine that amp has tube driven reverb? 1st place to look is the driver tube.

[Ice Man]

Re: Reverb Issue on my Boogie

Yeah,
I should have mentioned all the preamp and main tubes were recently replaced with new JJ's. Same problem with both sets (new and old).

[Guitarist]

Re: Reverb Issue on my Boogie

Have you called Customer Support?

[Guitarist]

Re: Reverb Issue on my Boogie

Sounds like something a professional would have to fix...

[Gearjoneser]

Re: Reverb Issue on my Boogie

First, swap out the tube that drives the reverb. Also, unplug the pan, take it out to make sure none of the springs came loose or has any broken wires, and reinstall it. Use contact cleaner or alcohol, and clean the pot that controls the reverb. The pot's travel could be dropping out from oxidation......reverb knobs don't get turned as often as others.