Derek
I have around 1700 of these in a 1 on 1 setting in our school district. I have found the mouse pad moves and rubs the side of the opening causing it to not click and feel non responsive. It gets too expensive to replace the keyboard top assembly, so I found if you cover the keyboard to protect it you can heat the mouse pad with a hair dryer insert your pry tool beside the mouse pad you can move it till there is a gap all around the edges let it cool a second and remove the pry tool and the mouse pad will click again.
Good luck
Jeff