Hi, I have a 312-8 with a 48" deck. The right spindle slowed to roughly 1/2 speed while mowing. I could tell as the right grease fitting was spinning slow and cutting not so good on that side. I just greased it before I started and heard a thud or something after a few minutes. Don't think I hit anything. Took off the deck and covers. One deck belt drives all pulleys. Everything looks fine. Idler, spring, tension, etc. I just don't see any damage. I held the spindle with my hand and the blade seems well connected. Everything moves and spins freely. any guesses before I put it back on? Thanks, Skyler