I had to adjust my wipers since they were resting and hitting to low on the rubber around the windshield. After removing the nut, I had to use small bearing puller to get the wiper off. It is similar to your wiper Dave, except my wipers had a soft metal sleeve inside the wiper arm that would conform to the splines on the wiper drive shaft with no definite spline showing. This is what locked the arm to shaft requiring bearing puller. Looked like some electrolysis was starting also.
MR 2015 Thor Vegas 24.1 in Ocala