Small Engines (Lawn Mowers, etc.): Craftsman riding mower with Hydro Gear Transaxel, hydrostat not pulling

Question
Still moves along but beginning to develop a slip or hesitation that sounds like ? a bump or something about every 2 to 3 feet of forward movement. It does go forward or backward. I haven't opened the mower up yet to get an eyeball on it but I can feel the transaxel fan is free to spin by hand. Can't feel any cracks in it. Tried to tighten the lock nut on the top of the pulley shaft. Clamped the belt to hold the pulley. The nut was tight. It was hard to reach and could only get one hand up on a wrench. Have you seen the fan hub break before or could this be internal to the transaxel? Craftsman 917.272263 Hydro Gear 323-0510

Answer
The fans break often.  The first thing to do is remove any cause of overheating.  Clean the transaxle and be sure the fan is in one piece.  These are the most common problems with hydrostats as they cause overheating.  Check these two things and let me know what you find.  Thanks, PK.