I have a Capital COB304 Connoisseurian dual fuel range. I was following a recipe that said to put a sheet pan on the top rack and preheat the oven to 500F. A day later I noticed a cracked door glass and it must have been from that preheating episode. Has anyone else experienced cracked glass? I have never run the self clean cycle and now am in fear of doing that because the oven floor and the broiler are also glass and if you buy parts from Capital now they are outrageously expensive. Their support sucks too now but that is another story.