i have the same problem. the problem would be resolved with a shorter hydro filter but not sure which one would match up. what toro refers to as the deck struts are worn but the side to side movement isnt significant. it is mainly when the deck pushes up on one side from the scalp wheel any hits the filter(which has bad wear marks on it now), which in turn pulls it off of the idler pully. have new struts on another unit and have the same problem.. i feel your pain shappie!