I bought a 2005 Craftsman 13.5 HP 30" mower from a guy who barely used it but he had bought it from a previous guy, Model #536.270301. Overall, the mower is in good condition and have used it since I bought it in July. The 16th of September, I started it up no problem, but the blade does not engage for some reason. I was reading the troubleshooting manual and it stated that if the mower blade does not rotate, to replace the mower drive belt. After looking at specific part numbers, in my manual, I'm unsure of which belt to replace: There is a Repair parts Motion Drive, that lists Key No. 71 as, Part No. 37x129 Belt, Drive. What confused me though was there is also a Repair Parts page for Mower Housing and it lists Key No. 1 as Part No. 37x111 Belt, Blade Drive. If anybody can help me out regarding this issue. There is a retention pond behind my house that overflooded from this past weekend and my grass needs to be cut. Thanks.

Keave the engine off, engage the blades and put it in gear with the clutch released. Get under the tractor and check every belt, they should all be very tight, are they? Your model is a rear mount engine so belts are tough to reach but someone else's hands installed them so there is a way.