Tremolo Effect Mod

I built this tremolo effect a while back and I absolutely love it. While I enjoy simple DIY projects, I'm no expert, and I don't have enough experience to know which components do what. After months of use, I have found that the only thing I don't like about this pedal is that the depth control doesn't take the effect all the way out at its lowest setting, in fact there is still quite a bit of tremolo depth. I'm wondering if there's a simple mod (probably a resistor?) that will allow me to increase the the lower range of the depth control. Thanks for the help!

http://www.generalguitargadgets.com...d&phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

R7,R13, R19 sets the amount of effect. Short out R19 will allow the effect to go to zero.

Shorting r19 will give the same max effect as now, but as ron says when turned to min there will be no effect at all.
Nifty circuit, a transistorized version of an ac30.

Thanks guys, I pretty much figured that out after asking the question, but I was so glad to have some definitive help. It worked and all is well.