With a bad seal, I never had the curtains get wet even in the FL rainy season. But the road dirt was bad enough. The clincher was when camping, at night we often get into bed with the lamps on and do our email/texting for about 1/2 hr. The bugs, no-see-ems etc, would follow the light thru the bad seal. DSO said fix it.
After separating the top and bottom (easier than I thought), I took my time and did everything correctly, and also did some much needed cleaning. Lowering the top took coordination, but went very smoothly.
An air compressor with a good staple gun and weatherproof staples made the job quite easy. Our surprising total time about 6 hrs complete. I DID use 4 X 4s instead of 2xs on the corners the 2 X 4s across the corners and went from there.
Just take your time. You can find separating the halves in the "search" heading at the top of the forum.
Tree