The problem is that Monaco switched wiper suppliers in the vicinity of our model year, going with what turned out to be a lower quality product than they had been installing. When my drivers wiper arm failed at the pillar post a year ago in a snowstorm, Beaver Coach Sales recommended replacing both arms with newer technology "Boomerang" style arms and blades, so I had them installed. Although a bit shorter in length, they are supposed to be better built, and I can affirm they do a whole lot better job of clearing stuff from your line of sight. They apparently don't make the OEM arm anymore anyway. I'm not surprised.
I know this may not be the quick fix on the road you were looking for, but you asked for any input. If you can wait until Monday, give Ken Carpenter at BCS a call then. The arm was a "28WET" and the boomerang blade was a "28I", according to my service receipt.
Joel