Have you ever tried to impress someone by picking one of those Master combination locks and failed?
The Master lock company made their older combination locks with a protection scheme. If you pull the handle too hard, the knob will not turn. That was their biggest mistake.
The first number:
Get out any of the Master locks so you know what is going on. While pulling on the clasp (part that springs open when you get the combination right), turn the knob to the left until it will not move any more, and add five to the number you reach. You now have the first number of the combination.
The second number:
Spin the dial around a couple of times, then go to the first number you got. Turn the dial to the right, bypassing the first number once. When you have bypassed the first number, start pulling on the clasp and turning the knob. The knob will eventually fall into the groove and lock. While in the groove, pull the clasp and turn the knob. If the knob is loose, go to the next groove, if the knob is stiff, you have the second number of the combination.
The third number:
After getting the second number, spin the dial, then enter the two numbers. Slowly spin the dial to the right, and at each number, pull on the clasp. The lock will eventually open if you did the process right.
This method of opening Master locks only works on older models. Someone informed Master of their mistake, and they employed a new mechanism that is foolproof (for now).
The older models are from 1988-1990. The newer models are being cracked on as we speak..