When the combustion chamber insulation falls in these and causes the case to rot / melt / distort through where does it usually go, is it obvious on removing the burner?. Got one hitting about 1000ppm co in 10 seconds and getting a co reading of 250ppm from behind the burner. I'm going back to attack it in the morning as I had just spent 2 hours scraping carp out of the sump and trap!, I know it's scrap I just want to satisfy my curiosity.
