I took my wiper motor apart and cleaned and regreased it, really not too hard. The wiper gearboxes were another story, the chrome nuts that hold them on from the top were very stuck, couldn't get anything to come off without twisting the sheet metal. I soaked the boxes with WD40 and maybe some brake cleaner to thin out the old stuff, then used some spray lube, but without getting in there to really clean everything out the wipers are, as Jerry said, SLOW