IF you will put some arrow marks (with tape or marker) on the mirror with the hole rubbed in it you will see right away which way the alignment is off. I used this system for 25 years aligning graphic arts cameras at the time of installation and later in service calls. What happens when you look thru the mirror is like when you are sitting in a barber chair and the room has a mirror on one wall and a mirror right across the room. You see the reflection and the reflection and the reflection until you cannot see it anymore. If the alignment is off the arrows will trail off in the direction of the error. If it is in alignment the arrows will recede straight down the optic path by just getting smaller and smaller.

lee\c