Harold41, I've got a similar problem with mine! By asking your question, you've describe how the end of the shaft looks. The PO welded a hex-nut to the end of the wiper shaft to be able to fit a wiper arm from something else on it. I cut the nut off with a die-grinder but the hole and groove on the end of the shaft are gone, filled in by the weld! I've got a new wiper arm but can't figure out what to do about the shaft.
