The broken part (yoke) is either phenolic, bakelite or fiberboard (pressed wood fibers in a resin). I would also consider fiberglass-epoxy laminate. The attached pictures may be helpful for creating a replacement part.
The arm(s) on the motor, wiper linkage and the tower arm determine the distance of the cleaning (wiping). Wear of these parts can make the distance longer and shorter. The position of the wiper arm on the grooved drive determines beginning and ending points.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
