It's a little difficult to explain but the secondary should be a few mm both toward the primary and a few mm away from the focuser.
I have looked at my Skywatcher 12" and it looks factory offset, ie: the center shaft support for the secondary is not attached to the physical center of the mirror but slightly towards the upper edge. So naturally the secondary mount is dead center of the OTA but because of the off set mounting it is away from the focuser.
A bit of a read but great inpho.....
http://www.atmsite.org/contrib/Carlin/collimation/