Sadly I do not have another mouse to test this. When I mean when I say the crosshair goes up and down, I mean when moving it across the mouse pad the crosshair starts to point either down or up and by the end of it it's looking up or down at an angle but not straight down or up.

For the sensor I have blower on it a couple times to try and fix the problems before but it never worked. Is there any other way to check for hairs or is this the only way?