My daughter's winter coat zipper would not "start" -- the end of the zipper was a little frayed and it wouldn't fit into the slot on the bottom of the connection side (a little hard to describe. . .)
So, I thought, if I could just widen that receiver end a little. . .but the zipper is plastic, and I didn't want to crack it--so here's what I did :)
I used a table knife to kind of wedge it open a little more and poured boiling water over the zipper end in a cake pan, and let it sit in the hot water till it cooled. Then I put ice water in to chill it up, and . . .VOILA!! :) It opened up enough to zip the coat easily!