OP. Someone adjusted the springs after the weight was added. That is the classic symptom of springs that are too weak, I repeat weak, for the weight of the door. They were overwound trying to compensate for the added weight. You cannot adjust your way out of this issue. Best way to get the correct springs is to get an accurate weight of the door in its rested state. Bathroom scale in the center of the door, close the door by hand then with a round winding bar, not a screwdriver, take the weight off the springs by turning the whole shaft, until the cables have a little slack. Just enough to be loose not loose enough to jump off the drums. Good luck.