Very thorough, thanks, but would like to offer a simple alternative that may apply. After several years, my MLM 5000 scroll wheel became very difficult to turn; thought I'd have to disassemble and clean it. Actually, the rubbery plastic coating on the wheel was shredding and rubbing against the outer casing, so I pried up a section of the coating with a small screwdriver, cut through its width with cuticle scissors, and peeled/rolled it off the wheel completely. The scroll wheel is now PERFECTLY smooth -- better than it ever was or than ANY other mouse I ever tried. Really love the feel of it now. And without the extra padding, my index finger now rests 1 or 2 mm lower, which I find a little more comfortable. The only drawback is with the slightly reduced height, it's very minimally more difficult to scroll horizontally (tilt scroll). The resistance is unchanged, but there's that much less surface to push against horizontally. Vertical scrolling (rolling) is great now.