Peter;

This is an old thread so help may no longer be needed...but I'll add it here anyway...

Dylan;

I can't speak to 544 wiper motor specifics (they are NOT interchangeable with those of a 122), but in general terms, wipers can be sluggish for mechanical reasons (shafts in bushings through cowl bound up...they must be free to turn and preferably well lubed, and motor should itself should not be running slow because of mechanical drag)...or electrical reasons (low voltage at motor, assure good ground at motor and no voltage drops in supply voltage).

The fact that Park Switch is not working suggest that a removal/inspection/refurb is in order anyway. Once you disconnect motor from linkage, that's the time to check for free bushings through cowl.

122 Wiper info might help: http://www.sw-em.com/Windshield%20Wiper%20Systems.htm

Good Hunting