In our specific situation, there was a small gap in the gasket----perhaps just a slight miscalculation when measuring the length?---and it was there, where there was about 1/2" of no gasket, at the bottom, that we noticed it. only happened when the awning
was not in use, as you might expect, and during heavy, heavy rains. it caused that removable carpet to get wet for about 2-3 inches just inside the doorway. We didn't replace the entire gasket. He sent us a piece of about 18 inches length and we cut off enough of the old gasket to totally snug it in, so about 17 1/2" in our case, to compensate for the gap.
No problems since.