Never heard of this before. Been using and learning about Trimmers since the early 1960's at my Dad's knee.

The roller is chain driven from the main jackshaft, so it's a positive drive. However, the rubber tread on the roller is bonded to the roller's metal structure. It's possible that the bonding failed and the rubber cover is slipping on the cylinder. See if you can move the rubber tire relative to the cylinder.

If the rubber is slipping you can remove the roller assembly (disconnect the chain, then remove the two u-bolts), pull off the rubber and try to re-bond it using a high strength adhesive compatible with rubber and metal. A new replacement roller is p/n 25601 and is $118.50.