I'm having a devil of a time getting the board sensor clean. I bought a can of compressed air but can't get the nozzle to spray on the sensor without turning the can upside down (which it says not to do). So I tried cleanex tissues dry and wet then dry and managed to get the sensor clean one time but after one short job I get the sensor error again (400). It's a real pain to crank the head up so that I can get under it to wipe the sensor and back down only to get the error again and again. Does anyone have an easy way to clean the darn sensor the first time after a job? I'm really getting to my wits end. Help -- Dick