If I recall they had fiber floats and if they get old, soak up fuel and sink,brass ones would be a permanant fix.I always had trouble with leather accelerator pumps too,then they went viton,leather would curl up and give ya the big back fire when you tried to floor it.Took me years to figure out air door setting,do it by feel now by pressure tapping on it and how lightly it closed.Have not ran thermobog since 80`s on my several 440 new yorkers......