Craftmans 917377271 selfpropelled mower, drive belt will not turn, so am assuming the keeper key is stripped on motor shaft. How do you replace it.

Hi,
Check to make see that the belt gets tensioned, that the transmission will engage if done manually. The keyway is cast into the blade adapter. No parts breakdown at SearsPartsDirect(unusual) but the owners manual is at ManageMyLife. Best way is to remove blade and adapter to check and carry the adapter with you if needed. Manual:
Owner's Manual - CRAFTSMAN Walk Behind Lawnmower, Gas 917377271 - ManageMyLife.com
Peace,
Clarke