So I was reading up on this issue and heard the DNA does not replace them under warranty as they do in Canada. I then read all these forums on this site and others and decided to wing it and use oven cleaner as some suggested to remove oil and discoloration. I used the yellow can and allowed the bike to heat up first. DO NOT DO THIS. It worked great at first but then I left it on a tad bit too long, maybe 2 minutes too long, and it took the powder coating off the horiz head and burnt the finish. I think the blue can of easy off might be better because it's less caustic, but I'm done with experimenting. Now I have to ebay or source new heads and replace because it looks like trash. Anybody know how complicated/expensive it is to either recoat or replace the head covers? I don't need new internals of course, just want to change the cases or refinish. I might have to spray hi temp color match paint on it until I figure this out. I was going to just mask everything off and try to shoot it on the bike.