I tried to get pics, but it is too small to see well at my cameras closest focus. The divot (melted spot) is directly across the edge of the sealing surface, going about 2/3 of the way down the sealing surface. It is indeed where bubbles form when sprayed with soapy water. I don’t think there is any lip preventing the seal, I suspect it is just missing rubber. I will pull out a magnifier and look more closely.
As I suspect that I will have to replace it, I thought it might provide some experimentation opportunity for repair. I have already ordered the replacement zipper.
First try I coated the other side and the surface of the zipper with lube and ran the slider back and forth a few times to get it well coated. I plan to close it and fill the melted spot with seam grip. I may have to trim some of the hardened seam grip after it sets, but the zipper lube should prevent it from sticking to the parts I don’t want it stuck to…. Has anyone tried this?
will post results.