There were two versions of the Plimsoul.
The Plimsoul is possibly my favorite distortion ever. I've owned
three different revisions.
The first one (my favorite) is closest to the patent, but every single build oscillates. Three different PCB layouts (two not my own) and two different vero layouts (neither my own)... This one still haunts me to this day. This one used two 1N916A and one 4.7V zener diode for clipping, and an A100K Drive pot. I've traced this circuit from three different units, and compared against another persons trace... The schematic is correct, but the damned thing just won't stop oscillating. Is it the component placement? Probably... But five completely different layouts all behave exactly the same way.
The second one was similar to the first, but only had a single RC filter on the feedback loop. This one works great, and was the inspiration for the SoulDrive PCB. This one used three 1N916A clipping diodes, and a B1M Drive pot.
The third one also had a single RC filter, but uses 5 1N916A diodes for clipping and a B500K Drive pot.
Each one had scattered component value variances... 1K / 10K series input resistor, 470R / 1K filter in RC network between gain stages, cap (or no cap) across clipping diodes to ground, etc...
Random note, I was always intrigued by the similarities between the Plimsoul and the Peavey Tube Sound Distortion.