I've had to replace the float sensor on my JBJ auto top off twice now and it's been running fine for over 7 years. I was having similar issues with the lights staying on and the pump not running. Float switches can be found for cheap on fleabay.

I've cleaned both float sensor today, and see what happen. I might replace the float sensor as well. Thanks.

This is old thread. My JBJ ATO was working fine until yesterday since first problem but somethings happen again. The pump doesn't stop. Both sensor 1 and 2 works fine but main controller fail. I'm thinking to get new ATO before disaster. What is your recommend? I've searched and Tunze Osmolatar seems really good one. Does anyone who own this ATO has any problem? All I see is good comments. Your information will be very helpful.
Thanks