Welcome to JUST ANSWER small engines, let me try to help you !! You mean the key on the bottom of the engine that is for the drive pulley and deck pulley? Would have to remove the deck, then use impact , electric or air to remove the bolt in the center, then pull off the pulleys to get to the shaft.??
no, the woodruff key on the pulley that drives the gearcase
The pulley on top of the transaxle?
Not your normal trans axle. Same thing, remove the snap ring, pull off the pulley replace the key. reinstall the pulley , reinstall the snap ring.
Well that means you have to drop the trans axle as there is no room to get to the pulley, due to the frame being in the way. Am I correct?
Afraid so. sorry.