Warning: you should not remove the mirror unless you have a reason to.Remove the 6 little screws holding on the mirror

Olexander warns: "O.. This is very rash procedure.
If you will remove the mirror disk, you will destroy of previous adjust of position of mirror disk ( influence on sharpness of image on film ), previous balance of swash of mirror surface of plastic mirror disk.
If you don't have collimator, not need do this, because, you can have problem with sharpness on film. "