Yes, the flange on the little black clutching pulley has broken off, and must be replaced! BT/DT: RustyJ

Check all the idler pulleys both V and flat and make sure the pensioner isn't bound up... common on a Scotts Murray.

While you're there make sure the cooling fan on top of the trans is clean and clear of debris.

Thanks for the help. I'll check the rest of the pulleys and clean the fan.

I can't seem to find that clutching pulley on the parts diagram here. I would think it would be under motion drive.

http://www.partsandservice.com/html/Murray/lt/lt46561x8.html

Any ideas?

Here is a link that might be useful: Murray Parts 46561X8

There is a pulley that places tension on the drive belt when the parking brake is released.

Items 55 and 56 will do the trick. Commonly available I'd think at a local shop if you are so inclined. Any Briggs dealer can order if they don't happen to have them.

You should also check the transmission mounts to the frame to insure they are intact. On my MTD rider they rusted out; the transission moved a bit when the clucth was released and the belt jumped off!

I replaced the 56 pulley but that wasn't it. I took a few more pictures of that bad pulley, to try and figure out what part number it is. The diameter of the hole is 3/4" and overall diameter is ~2 inches. (assuming not alot of plastic is worn off).

The reducing bushing that fits inside is an inch long, and takes it down to fit a 3/8" bolt.

Any other ideas as to the part number?

{{gwi:356206}}

Ref 56 is a V idler and the other #55 is a flat idler. The flat one was worn in the pic