[dkarb]

Some people are not aware that the wiper speed is controlled by turning the dash knob clockwise to speed up and counter clockwise to slow down.  The guy I bought my '87 from said the wipers wouldn't work unless the windshield had water on it.  I turned the knobs clockwise and they about flew off the windshield they went so fast.  He'd had the coach for 3 yrs and didn't realize this.
I also replaced one of the wiper motors on my '81 with a rebuilt one and it wasn't that expensive.  The same company will sell you a rebuild kit for yours if you want to go that route.