Try Richards Gravely in West Virginia.
They used an odd friction material, not like used on an automobile. It almost appeared to be a reenforced Polyurethane material like used on skateboard wheels.
The PTO clutch piece on the later 800-8000 and G series uses the reenforced Polyurethane like material on them also.
I don't think you'll find anybody to be able to re-line them, but good luck if you do..

Thanks for responding. I talked with Jamie at Richard's. Only had used ones for $90.00. He never mentioned re-lining be did mention others trying strips of leather, etc.
Called Ariens-Gravely, no replacement. Jacks Small engines had one listed but not available. Looks like most recent MSRP on one was ~$287.44. One on ebay currently, NOS, bid of $100.00.
If you or anyone else has additional similar information. Please pass on.

That'd be about your best bet, would be checking EBay, or going with a 'Used' part.
I would trust Richard's, even for a 'Used' part. He's honest and would let you know if it would work ok.