Sorry that I did not see the post on the weekend I would swab the backside of the board saly and other stuff can creep into the unit. I have not have a problem like this but if it is from creep of some kind this should do the trick. If this dose not do the trick there maybe a solder joint that is bad and cleaning the board with the swab only forced a conection temporary. I would then take it to an elctronic store and have them go over the solder joints they will know what they are looking for.

One other thing you can do to test is to have the unit open and plug everying in and wereing rubber gloves have it so the red light is on and the pump should be running then gently put presure on individule componets that are on the board when you come to the part that is not making contact the pump will start this is the part that needs to be soldered or replaced take it to a electronics repair store do not do it your self. but you can save on the repair bill because you have found the part that is not working properly.

I do not recomend doing it your self unless you know what you are doing and have the right equipment like a temperature controled solding iron or a pace sodering station about $500-$700. You can damage componets with to much heat.

Bill