I've had the same mx518 for 12 years, one day the mouse wheel stopped working and I found this inside. Enough hair and grease to completely block the sensors. : r/hardwaregore
Retired my trusty MX518 after 11 years good service! (+ mini review) : r/MouseReview
Logitech MX518 (V1) Cleaning/ Mods
How do I fix this scrolling issue in my Logitech MX518 mouse? - Super User