Quoted from Solder_Splash:
Yes but in order to calibrate that, you first need to level the machine with the glass off.
In theory you could build a database of machines where you list the game title, level it to a perfect 6.5°, and then check the glass level and record it. Then anyone would be able to walk up to that game and level it off the glass. Might not be *perfect* every time, but should be damn close, and more than good enough to fix on location games and the like.
I wonder if all modern Sterns say, have the same relationship between playfield and glass, or if it varies from title to title.