[Gromit]

These flaps are pretty easy to refurbish - I like the previous poster's evaporust idea... mine only needed cleaning and a little brillo pad and elbow grease and a shot of paint.

I got an 8-1/2 by 11" sheet of self adhesive 1/16th felt; and a similar sized sheet of self adhesive 1/16th neoprene foam (the peel-off type) and sandwiched them together and pit them between the layers of sheet metal. I only settled for the yellow neoprene because they were all out of the black.

You can get those sheets of felt and foam at Micheal's Art & Craft Supply

Anyway; here is a photo - I drilled out the factory rivets and used screws - but probably pop rivets would have been better - you can snip off the screws close to flush..

This isn't for the factory correct guys but if you just want it to work and stop the deterioration and rust and air and water leaks it works okay; and is reversible if you want to go back to the way it was..plus you save $90 to spend on taking the war department out to dinner!