If it's grinding on the cast, it could be the pinion gear not completely disengaging while in freespool- Could be the yoke that holds the pinion getting worn, but MagMaster will know for sure- I'm sure he'll post on Monday and help you out. If it's just a noise, could be a bearing on either side of the spool shaft or the bushing on the shaft, more of a high pitched sound then a grind.