Hi we had a hard time finding this gasket and we are a P.E/Piazetta dealer lol, the last tech training I went to the factory rep said we can use high temp rtv if gasket was not available I have done it several times no issues you also might want to put never-seize on that bolt you took out they have a history of seizing up and are a absolute nightmare to drill out.... Good luck
Sootmaster: OK I'll look for the hi-temp rtv. As for the bolt, I gingered it out and that was my big worry, snapping it off. It should be hi-grade, or how about the maker making it bigger. Not overtightening would be a good idea too.