Repaired mine the other week.
The 'hub' as you call it is simply a plastic spacer tube/bearing, and you can removel it from the shaft.
What has happened to yours is; the output shaft has rusted up internally. The 'hub' spacer tube is also keyed to stop it rotating so I suspect yours is going to be damaged.
On the output end of the shaft (wiper arm end) is a small c-clip and washer (normally covered in rust). Scrape rust away, WD40 and remove clip, pull plastic spacer off and clean up shaft (there is also a small o-ring on the output end of the shaft to stop water entering!!). I'd recommend you go the whole hog and open up the back of the gearbox (4 torx screws) and knock the shaft out to clean it up properly, as there is a metal bearing within that rusts up as well. Be warned the shaft will be really rusty, clean it up and use lots of grease when you put it back together. Before you fit the wiper arm back on, power the motor up to set the park position.
Hope this helps