Try lubricating it and see if you can get the paddle to move freely. What the heck, shoot some WD-40 in the lubrication ports. Perhaps the seal is gummed up, dried out, and/or cracked?
Maybe someone knows where to obtain a rebuild kit, if there is such a thing. Ficken's Wiper Service does an excellent job of rebuilding a vacuum wiper motor. That's where I got mine rebuilt.
http://www.wiperman.com/http://www.wiperman.com/rebpagewpix.htmlNote:"What surfaces or materials are OK to use WD-40 on?
WD-40 can be used on just about everything. It is safe for metal, rubber, wood and plastic. WD-40 can be applied to painted metal surfaces without harming the paint. Polycarbonate and clear polystyrene plastic are among the few surfaces on which to avoid using a petroleum-based product like WD-40."
