[Harp-L] dirty, crunchy harp attack pedal

[ian osborn]

i sent lone wolf a message for help, but curious if anyone else experienced this...
i use a shure green bullet mic with a harp attack pedal and plugged in the other day only to find some static and popping coming from the mic when i changed the volume, and louder than usual popping when i changed from clean to distorted/overdrive...
 i plugged my mic directly in without the pedal so that wasn't the issue. 
i'm going to clean it with some compressed air, any other suggestions??
i also only usually use the battery power rather than the power supply.
thanks
ian