Hi, Bought a heat n glo sl-750tr-ipi-e from Craigslist never used. With my lack of knowledge purchased took it home read manuel found out once a vent direction is chosen it can't be changed. Well back to my lack of knowledge the top seal cap was removed and I can't use it that way. I don't have the cap either so I need to use the back vent. The book says you can not reverse this choice. I need any suggestions why I can't put fire resistant insulation back in the top hole and cover it with some kind of thin steel. Maybe someone here can shed a little light on my situation. Thanks,Bitter