I have never had that happen with any camera, so not sure of exactly how the glue is applied. It would seem to me that four spots of glue could be applied at varying thickness's and if so would ultimately decide the position of the mirror, closer or farther from the lens mount and up or down. It may only require a fraction of a mm to make it throw out the image on the screen. Also, in the film days Minolta had a small mirror that controlled the focusing in some way. Does Sony do the same or have they incorporated it into the main mirror? I don't know, but if they do, then the focussing may have to be reset also.
I am unable to check my A850 to see how it works as I have left it at my daughters. To me glueing the mirror does not seem to be a very high tech solution.
Sony A7, A850, A77, A700 || Sony>> 70-300G, 28-75 f2.8 SAM, 16-80CZ, 50 f1.4, FE 28-70 OSS, FE 24-70CZ f4 OSS, LA-EA4 || Minolta>> 300 f4 G HS, 200 f2.8 G HS, 100 f2.8 (D) Macro, 50 f1.7, 28 f2.8, 28-135 f4-4.5, 70-210 f4, 500 f8 Reflex, TC x 1.4 HS, TC x 2 HS. || Sigma 21-35 f3.5-4.2. || Tamron SP 24-135.