Are the pins securing the tines to the shaft sheared? If the wheels are still under power, the belt is not the issue. The only thing left is a problem in the transmission.

slipping belt will cause this problem!!

I also have this same tiller. Can you tell me the engine pulley diameter. I also need to know the belt size. Thanks, Tim

Probably not the proper forum to ask on but can anyone please help lead me in the direction where I can buy a sprocket part number 106142x for model number 917n 299253. Sears no longer has and I can't find anybody with one on line, thank you Tom.

i know this is probably to late to help the posts here, but i hope it helps someone down the road, the sprocket for theses cannot be bought anywhere anymore, but if you take the old gear/sprocket to a machine shop they can make you one for around $50, they use the old gear and order a new sprocket to attatch to it.