I have to replace my thermostat, and the part shows it comes with a rubber o ring, but there is also a metal seal that is sold separately and I am unsure if this needs to be replaced, or if the one that is in there is able to be reused. The metal seal is $50, and I'd like not to have to buy it. Has anyone done theirs and what was your experience with these parts? Thanks for a quick reply, I have 1 hour to order to make the UPS cutoff! I appreciate any help.