Well, to begin with the straw chopper drive belt is wearing into the straw roller shaft, not whatever you said. Yes it is a common problem. Problem is made worse when the straw chopper pulley is worn and under size. A worn straw chopper drive belt will also run lower in the pulley and be more prone to rubbing on the straw roller shaft. If the straw roller drive belt is over tightened it flexes the shaft up into the straw chopper drive belt. Bearings going out on the straw roller will also help to make the issue slightly worse.