I have a Rheem hot water tank. When I hold down on the pilot light button & push the igniter, the pilot light lights but when I let up on it so I can turn on the burner .. it goes out. It's driving me nuts! I already replaced the thermocouple, purged the tank, cleaned all the contacts inside. The lines aren't clogged with any debris.. That glass/oil safety shut off seems to be fine. I can't seem to figure out the problem. There are no lights on the tank like other tanks have that may give ma a hint as to the problem. I don't know what else to do?