Hardware mods for Morley Volume Pedal?

[Dave_B]

While looking for some old magazines (Mark  ) I've rediscovered an old Morley Volume Pedal I purchased years ago.  I abandoned it because I could never get the piece of material to fold correctly (the material that blocks the light from the photocell) and control the volume in a nice way. 

Has anyone done any mods/adjustments to one of these to make it useful?  I'd like to build a wah circuit into it, but I've got to nail down the hardware issues first.

Thanks,
Dave