BOOM MAKES A SQUARING NOISE WHEN BOOM IS OPERATED BOOM MAKES A SQUARING NOISE WHEN BOOM IS OPERATED 6) 6) 5-21 YES Is boom foot pin greased sufficiently? NO Cause Remedy Boom foot pin has run out of grease. Frictional noise occurs between the sliding faces of boom cylinder's oil seal and boom proper. ※ Frictional noise will disappear if they are kept used. Supply grease to it. ※ If seizure is in an initial stage, supply sufficient grease. If seizure is in a grown state, correct it by paper lapping or with an oil stone.