The elevation screws work loose. There are 2 things that need to be done if you want to eliminate this problem.

The first is to go to the local hardware store and buy their smallest lock washers and take off the back plate, remove the lock down screw from each site pin and put a lock washer under the head of each one.

Step 2 is to ensure that the elevation adjustment screw is turned a little after you've locked the pin down so that it does not move at all. you can also add a small drop of goattuff or even super glue to where the screw and sight body meet.

This will take care of the problem.

Oh, I just found a new one yesterday. The screw cap for the LED will work loose over time.