In any event, removing the black plastic rails solves the problem. I am not certain why removing the rails is beneficial, but I have two guesses: These rails are not really necessary, as long as you use the mouse on top of a cloth mouse pad (otherwise you’ll hear annoying scratching sounds as your mouse slides over your table top. The black plastic rails have been problematic for years, as they kept falling off.
Much to my surprise, removing the black plastic rails allows my Apple Magic Mouse to properly track motion when I slide it around. I found a simple fix that works great for me.
