The disgusting object in your hand
The mouse scroll wheel began to work very badly. If it had quit entirely, I’d have thought the optical emitter or sensor had gone dark but working badly means it can be restored to full function with a simple clean-out.
This mouse is 7 years old; it was made for a laptop but I’ve used it for both laptops and desktops. I’d say that it has certainly delivered value for the fifteen bucks I paid for it, but what the heck. I took out one screw and popped the two halves apart. It’s the standard arrangement with the scroll wheel having spokes that interrupt a beam of light between an emitter and a sensor. And the actual mouse positioning is accomplished by fixed sensors on the underside that see the desk passing by.
Since it’s an optical mouse, I thought it would be cleaner inside than the old ball-style mice. How wrong I was: the scroll wheel acted like a little vacuum cleaner for cat hair and… something else. (Click on the first picture, then on the magnifying-glass to see the awful truth).
I don’t even know what that translucent beige-colored stuff IS, but… eeeewwww. I suppose most of the objects we handle everyday get this nasty inside. Anyway after a few minutes with tweezers and compressed air, the mouse is good as new.
One other thing: the mouse, like most mice, has internal ballast in the form of a heavy steel plate. Even for a mouse designed to be used with a laptop (where every ounce counts) I guess heft matters.