3000,
I knew you'd get it welded back together, despite what some others said
.
Fossil,
I wonder if you can just fuse the polyethelyne back together using a soldering gun? I've fixed an air leak in a plastic Rollez tire and welded a trimmer muffler guard back together recently using just a solder gun to melt things back together - no welding rod used.
I have a plastic boat that I believe is manufactured out of roto-molded polyethelyne (a Logic, later to become Triumph boats). Supposedly you can fix gouges in it by just using a heat gun to melt it back together.