The spring that presses against the zeroing nut should provide sufficient tension to keep the brass poise from moving. Check to make sure that the screw that holds the poise is turned in so that the shoulder of the screw is tight against the frame of the beam. If it is, and the poise is still loose, please return the scale to at the address below along with a note explaining the problem. We will inspect it and either repair or replace it for you.
Lee Precision, Inc.
4275 Highway U
Hartford, WI 53027