We're tearing this decrepit Maxi a new one, and we've come to a contention point: try as we might, pound as we do, we can't get the drive sprocket to come off. We took off the front circlip and have been wedging, pulling, pounding, pleading it to come off. PB blastered, bonked with wooden mallets... Could it be glued on? Why? Any wisdom, wizards?