Inside

What you see here are the innards of a volume pedal which had its base plate removed & tilted sideways. If yours becomes dysfunctional, the chief culprits are labeled above:

• A: Rack gear. This contraption looks like a saw blade, it's attached/ connected to B. The rack gear moves up & down as you rock your treadle. The rack gear might snap under intense use.
• B: Pinion gear: The pinion gear you see here is rather large, in many wah units, the pinion gear is attached to the pot's shaft as standard issue. This contraption might break under intense use as well. The manufacturer usually applies lubricant between these gears to prolong their good lives. We know that moving parts which are in contact with each other wear out over time.
• C: Pot. Over time, the pots in the volume & wah units wear out or they disintegrate internally & you'll hear scratchy responses instead of smooth volume swells/ wah voicings.