Hello
Well I know that I need a new spider gasket for my multi port valve(Purex Triton, model SM20-2). I ordered a new one from pool store. Problem is though, it seem a bit smaller in diameter than what's in place now. The pool store insists its the right one. My question is, are you expected to stretch these a bit to fit in place or should it fit perfectly w/o stretching it. I don't want to remove the old one till I'm sure I have the right one

Thanks in advance for any insights