How to replace the glass that reads the trackball?

I have a Logitech M570 mouse. the little glass that is inside of it (I think it is the sensor that reads the trackball) got scratched, and now it is not working. The mouse on the computer moves in random ways.

Is there a place I can get that replacement part for this mouse? I tried looking everywhere, with no luck.

Thanks for any help you can provide.