It could very well be that the plastic gears that are cast inside the wheels are worn. As the teeth goes away, that causes a skip and eventually plastic wedged between the wheel and gear and there ya go. A 9/16 socket removes the nut in the wheel center. Wheels will run ~ 30$ a pair. It would be a good time to service the wheel drive clutches as well if you are up for it. On these the clip comes off, the gear slides out and a pin slides through the axle. Be mindful that the pin can drop out when the gear is removed if the axle is in the right position. Clean the works up, grease well and reassemble.

I see that a few times a summer. Usually the persons concern is that they have difficulty pulling the engine over or simply that the drive quit. The best you can do is to ensure that the lower guard is in place and the debris kept out. Also, these short belts have a lot to do and simply wear thin. 175436 is your belt#, it isn't one of the more common belts, but it can be ordered from Sears or any EHP dealer. It would be in your best interest to replace the belt with a new one and ensure that the drive pulley is clean before you put the belt on. You still want to pull the drive wheels and inspect those gears + lube the wheel studs and clutches. (Once a year :)

**Tom - thanks for the reply. When I dug into it, I found the fan belt had jumped off the drive shaft ( blade spindle). Was able to get it back on and mower seems to being doing fine again, Question is: Why did it jump off the pulley in the first place?
Paul**

Turns out the belt was off the drive shaft that blade is on. Got it back on and all fine. thanks to all.
Paul