This works with some Master Lock combination locks but may not work with all of them, especially not those that have no serial numbers.
Turn the lock’s dial clockwise to zero.
lock down if the shackle is locked onto something solid.
Find the first sticking point.
Release shackle tension and turn the dial slightly past the sticking point.
Reapply tension to the shackle and continue turning the dial clockwise to find all the sticking points.
Find the third number of the combination.
Find the magic number
Find the possible first numbers of the combination.
Find the possible second numbers in the combination
Cross out the numbers (the possible 2ND numbers) Plus or Minus 2 [25 and 29] from the third number of the combination
Figure out the correct combination by trial and error