I'm not sure I would go there, perhaps asking him to send you some high temp caulking, but demanding he come over and do it costs him money and time, it's a five minute job, working with the dealer would be a better choice in my opinion, let's face it, he didn't put the gasket in to begin with, I think I would also call the manufacturer or manufacturers rep to alert them of the problem, it has been a very busy year for all of us in the industry and sometimes things get overlooked, perhaps they are not aware of the issue and your call may fix the issue for other customers. The good companies do not look at those calls as a PITA but instead want to solve any issues before they get out of hand, from what I have seen on here, Heatmaster sure seems like one of those good companies to me!