Mr. Murphy,
I have a 42" model #917.271131, also. You might want to check the drive belt from the engine to the trans axle assembly. It's a seperate belt and it's located above the belt that powers the blades. so you'll have to drop the mower deck to get to it. If you have the manual that should have come with the mower, that will help a great deal - it takes a bit of disconnecting bars and stays, but it's not a big deal.
Art Lee, May 2005