1) Pull it apart clean the insides and check the sensor wheels inside are clean and in good condition.
you mean he needs to clean the mouse's ball????????
Oh yes.
I used to replace computer mice all the time, those 59-cent used ones gotten in thrift stores.
About three years ago, I finally figured it out, when I took one apart.
I don't know about anybody else, but the mouse here gets clogged, utterly clogged, with cat hair.
I really wish they wouldn't do it, but the cats here like to hang on to me, even though they've got this great big house and much of a great big outdoors, to hang around.
Anyway, I still have the same mouse I had that one time, three years ago; all it takes is opening it up and cleaning it out.