I just discovered a similar problem. The blak plastic protect cap cracked, causing the wipe arm stud to get VERY hard to turn. The whole aluminum crank mechanism would bend when the moter was try to rotate the arm. At any rate, I'm trung to find if the cap has a repolacement, and in the meantime pulled the crank mechanism out of the surrounding channel and cleaned things up. As for the motor crank being sheared, I's remount the crank mechanism to it, and solder or epoxy it. Replacements include both the aluminum mounting and crank mechanism.