8/13/2011 1:08 PM
If it's only one boom, I'd say check the o-ring on the valve for that boom.
If it is all booms, its the diaphragm on each nozzle body assembly. The diaphragms are supposed to hold the individual nozzle valve shut until a set PSI, usually around 5-7, occurs. This is so you don't get the drip. They are usually about $.10 each, and we replace them when we replace nozzles. The diaphragm is on the side of the nozzle body. The cap unscrews and inside is the diaphragm.