I built the noisy cricket and mine does exactly the same. I found it doesn't do much if anything. Just roles of the treble a bit when turning the pot anticlockwise between 11 o'clock and 5 o'clock. I was slightly dissapointed with this considering I'd chased that extra silver knob for the the amp all over the local area to find another. If I was to recommend the build, I'd say leave it out or change it to a different one.
When I realised mine didn't work (the position your in now) I decided not to risk spoiling my small amp head I'd made by trying to alter a small thing.
Just another thing I found it doesn't get very dirty unless I put a dist unit before it. Do you find the same?
I love my little noisy cricket I made (Or greenfly as I call it. If you look in my gallery you'll soon see why.

). I run it into my marshall cab and i use it for testing pedals and old shcool crunch tones where volumes just gotta be full which I can't do with a 100 watter for social reasons.

Anyway I hope this helps put your mind to rest thats you have most likely done everything correct and that it's a problem in the design. Well thats my opinion.
Hope you enjoy yours as much as I do mine. HAVE FUN!!!