momentary stutter-clicking and popping

[jolly1423]

I'm just trying to build a simple stutter pedal. I've done one before that just ran the lead wire from the tip through a momentary so when you hit the switch it just bypassed the signal and that worked great, nice and quiet. Not I've tried this one-
http://www.beavisaudio.com/Projects/StutterPedal/
Version 3, where the signal gets grounded and you can adjust the depth but I get a lot of clicking and popping from the switch, not loud but annoying. What's the deal, how can I clean that up? I made no mods and I've tried 3 diff kinds of momentaries.