Just dug out a rough copy of a mk6 airsporter which I think is the same trigger set up.
It says that trigger weight is increased by turning the screw "item 54" (thats the one at the front of the trigger)clockwise and vice versa. "The trigger stop screw (item 56- rear one) controls the engagement between the sear and trigger. Turn clockwise to decrease engagement or anti-clockwise to increase engagement"
I hope that is of some use.