Specifically, here you see the GREEN VINYL COUPLING that I made to replace the original white plastic broken fingers and circular tension band that are below in pieces on the table.
Basically, the movement of the seat- forward and back- is transferred to this rheostat through gears driven by a "slip coupling" that allows the rheostat to "self calibrate" as the "slip" of the gear driven pinion maxes out the variable resistor when seat travel reaches its limit.
The problem is that the fingers of the original white plastic ball "Palm" loose their grip as they break off at their "Knuckles". A simple piece of easily obtainable green vinyl fuel line holds fast to the square nubs of the original "broken wrist" YET, has the correct slipping tension when pushed over the coupler's driven ball. SEE the video operating my