Oh, bless. You enabled me to revive my M305! Its mouse wheel had ceased to scroll reliably. Following your instructions, I was able to clean out all the accumulated dust and hair and lint that was getting in the way, and now it works like new.
I would add just one more step: There is a screw towards the front of the mouse which holds the wheel down. Remove that, lift out the entire wheel unit, and then you can get at any built-up yuck that was trapped between the wheel and the board.