If you go to the Freestyle.com site they have a listing that will show the settings. You can use the variable contrast because your filters work like the VC filters that used to fit in the drawers. The setting will vary with each different brand of paper. My Beseler is a 67C head and takes the 82V bulbs so I am no help there. It sounds like an overheat limit switch someplace. If you could use a fan to cool the head of the enlarger it may help. I know you don't want to have a fan stirring up dust though.