i bought a used a old cva hawkin .54 cal shoots excellent but set triggers all messed up when bought set trigger did nothing (all the way back) and had extreemly hair trigger. adjusted set screw under triggers but now set trigger wont stay engaged. im assuming the previous owner messed with it. taking the lock off there is a another flat head screw that goes to the linkage on the back what does it do? is that the sear adjuster?