The second method for finding the third number is more exact.  When you tried the first method did you get 2 or more points that seemed like possible sticking points to you?  Then use this method!  It's a little confusing at first, but I say learn it.  In the long run you get the third number without error and fairly quickly.

This time instead of guessing a sticking point, you are going to guess a "sticking range".  Remember how your lock stuck in a small arc instead of one point?  Well now it's important to know that arc.  You must be able to estimate the low and high part of this range to a quarter of a notch on the lock.

Take a piece of piece of paper and make three columns (like 1, 2, and 3; or A, B, and C).  In these columns you will be writing down the sticking ranges mentioned above.

Turn the dial a few times to reset the lock.  Take your lock and turn the dial to zero.  Turn the dial left and find the first sticking point/range after zero.  If you don't know how to do this, read method one for finding the 3rd number.  Write the low and high end of this sticking range in column A.  Make sure to get the numbers exact to the quarter of a notch (I like writing xx.0, xx.25, xx.5, or xx.75).  Add 10 to the middle of that range and find the sticking point there.  Do the same thing by adding 20 and 30.  You should now have a column with four ranges.

Next find the second sticking point after zero; you will now gather data for your second column.  Get that low and high ends of the second sticking point, that point plus 10, 20, and 30, and put that data in the second column.  Do this one more time for the third sticking point after zero and the third column.

Now look at the decimals in the columns (the whole number parts of the ranges don't matter until you've discovered the range with the third number in it).  In two columns, all four low range decimals will be exactly the same, as well as the four high range decimals.  In the other column this pattern will hold true for three of the ranges, but in the fourth the decimals will be different.  Find the whole number between those two different numbers and you've found the third number of the combination.

The above can seem a bit confusing so here's an example:

Assume the above table is the data you collected.  In column A all the low range decimals are the same (xx.0), as well as all the high range decimals (xx.5); thus we know that the third number of the combination is not in column A.  The same type of pattern can be seen in column B (with xx.0 as both the low and high decimals), and thus that column can be ruled out as well.  Now look at column C.  Notice that in the third row of numbers in column C the decimals in both the high and low end of the range are different then the rest, (the rest being the same like in the other columns).  This means that the third number of the combination is between those two numbers.  There is only one whole number between 27.75 and 28.75, which is 28; thus 28 would be the third number in the combination.

Once you get used to this technique you can just do it in your head.  Once you get even better you can just do it by eye.  When going through the ranges in one of the groups, you would see that the arc in one of the four ranges is different; then you would find the whole number in the range.  When eyeing the third number of the combination, I do recommend checking your work, as finding the third number is the crucial step in cracking a Master lock.  Also remember that if in your first column you find the third number of the combination, don't do the rest of the columns.  As long as your sure, don't worry you've got the number.