12au7 then 12at7 from 12ax7, no difference. WHY!!

I've got a Tubeworks Realtube distortion pedal. I've heard you can tame them down a bit by replacing the 12ax7 with a lower gain tube. I tried this and there is no difference. None whatsoever. I even put the tube in one of my champs and it made a huge difference there, so it's not the tube. The guy who sold me the tube said he's heard of this not working in some realtube pedals but working in others. Did they change something in the circuitry, if so, can I mod it so it will make a difference? I can get the sound I want but I would like it to be a little less touchy so I can fine tune it alittle easier.

P.S. This is a "repost" but I figured with time between some new ideas may have come to light.