I would make certain that the rocker assembly is free of debris and sufficiently lubricated. The rocker is the spring loaded lever catch that is located on the the side of the lifter. To access the rocker, you can rotate the lifter out of the receiver with the trigger plate removed or it is just as easy to remove the lifter pivot screw and completely remove the lifter from the receiver once the trigger plate is removed. CP.
Note-you need to remove the butt stock to access and remove the hammer spring before removing the trigger plate.
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