After owning the Precision Adjust for some time, something that bugged me about it was that it would wiggle up-and-down and side-to-side. 

The support models that I've found out there only addressed the vertical movement so I designed this stabilizer which consists of three pieces, the main piece slipping on from the top to provide horizontal rigidity and the shelf/riser to provide the vertical support.

You may need to temporarily remove the back button to install the stabilizer, then reattach it afterward.