If its the crank assembly I am think of when mine failed both the dealer and Airstream said the never installed such a thing in their trailers.
A small crank feeding through the plastic lens via a 5/16 dia. shaft and into a small worm gear that raises the vent cover. If that is the one and the gear is stripped just take the gear box apart, drill out the rivets, and move the stripped gear 120 degrees. Only 1/3 of the gear is used so you should have 2 rebuilds available. Reassemble the gear box with #4 bolts and you should be goo to go.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles