Quincy, it sounds like you are trying to replace the spring with the hammer pivot removed. That doesn't really work as the hand interferes with the movement of the hammer and the spring tension is too hard to overcome to reinsert the screw.
I grab the bottom end of the spring with pliers and that gives you the leverage to twist the end to align with the slot and get it started into place. the tension screw is the last thing you adjust.
Long, if the spring pops out when you screw in the tension screw with the hammer down, it is either too short, or you turned the screw in too far. The chances are it will pop out upon firing if it's that close.