Thanks for this CK. However, I'm still lost. I'm assuming the micro switch is the white plastic thing with wires running in and around it, and the plastic tank is the white plastic right at the very bottom. How do I get into the plastic tank - there doesn't seem to be any opening, or anything. I've unscrewed the one screw I could see but that hasn't helped. Please tell me (step by step if you can) what I should do. Many thanks.
Tommy, January 2012