Is t fiber? Might keep the hole from "leaking". I didn't use any washers on my mini wsm and it leaked black gunk through the holes even though I had them tight.
Like Mac, I think it's there to keep the porcelain from cracking or getting scratched. It seems to add a little cushion (compared to a metal washer) plus it will form a little better to the curve of the WSM versus a metal washer. If I couldn't find them, I'd see about a brass washer and go light on tightening.
Ok, I'm buying the sealing part more than the porcelain damage part as that doesn't add up on other weber builds. Now I gotta find some without having to order from weber. What a pain.
well, took the brackets off the main body today. was able to save all the fiber washers except 2 of them. so the search is on for a replacement of some sort or i might be able to use the broken ones if i'm careful.