Hi, i had this trouble too, squeaking wah wah pedal very annoying. Solution was simple though, i used some WD40 on the pivot, towards the back of the pedal, not the part near the on/off button further back than that, where the hinge is between the top and bottom parts. apply some there and all is good hope this helps, that squeaking was driving me mad! (I didn't even use proper wd40 just some other cheaper brand version)
