I just changed out the rusty screws that hold the clearance light lenses with new stainless ones. The replacements I used were 6-32 x 5/8". They were a tiny bit big, but after the first two or three rotations they threaded on very nicely. The gaskets from the original screws fit perfectly. I was surprised at the amount of condensation under all
of the lenses.
Total cost: $1.10
Not exactly a major upgrade, but I sure feel better.