Anyone know how to adjust the Hatsan Sortie hammer spring? Hatsan Technical tells me to insert a 4mm wrench into the hole in the large brass screw at the rear of the frame and turn it. My problem is that the wrench does go in about 30mm and it seems to engage with something but I can not turn the wrench. I think there is a set screw somewhere that I have to loosen first but I can not locate it. I do know that there is a set screw for the large brass nut but I can not find the set screw for the hammer spring.