Sorry, I'm not expressing myself very well...
With the TRS-TRS cable the Moog came with and its switch set to Standard, the pedal goes from 0 to 100 to 0 again (or the opposite if I reverse Helix's Controller Assign); if I switch the Moog to Other and keep the Helix swapped, it works, but the pedal has to be rocked almost halfway for anything to happen.
With a TRS-TS Y-cord using the gray (ground?) plug, the Moog set to Standard, and the Helix back to 0-100/Min-Max, even with the heel all the way down the volume doesn't go all the way off, and the Position indicator won't go below 20% or so; with the Moog set to Other, it goes the other way - it goes to 0 but maxes out at 20% according to the Position indicator. (And I am making sure to set the Controller Assign to 0 and 100.)
Lastly, with the red (hot?) plug of the Y-cord and the Moog on Standard, nada. Setting the Moog to Other gets the best results, but that means the pedal is only responding from 25% to 75% of the sweep, and we're back, and we're back to the end of the last email.
At this point, it's kinda turning into a malignant brain teaser. If you have any neurons to spare, I'm open to suggestions; otherwise, thanks for your help...