Now that most of us are controlling the MuIII with an effects-loop, I'm not sure of the need for the addition of the True-Bypass mod (if you leave it ON all the time), and/or, the bypass-of-the-Gain-circuit mod.
Not sure but I think Richard originally offered those mods for old school usage where you run cords directly from guitar to MuIII to amp with no effects loop, so that the unit itself would not cause a signal Gain variation, and/or turning off the effect would not cause a non-True-Bypass tonal coloration.
'Just a thought to consider.
'All for Richards repair, cleaning, calibration, cap-job, on/off LED, etc....
I bought a MuIII from ebay that is cosmetically pristine except for one small chip in the paint, and, the Envelope Filter didn't work at all.
Sent it to Richard.
An Op-Amp replacement and general rehab service brought the unit back to life.
Richard also put the on/off LED (bright-blue) right where that chip in the paint was, making it disappear.