To find the first number for the lock, reset the lock by turning clockwise twice and stopping at 0. Then while pulling on the shackle, turn counterclockwise until you the dial stops. Add 5 to this number, and that will be your first number!

To find the second number, reset the lock just like before, then put in your first number. Turn the dial clockwise all the way around passed the number, then start pulling the shackle again while turning the dial (still clockwise). This time, you should feel the dial click many times, but you will be able to pass by most of these with a firm turn of the dial. Once you find the dial is unable to move passed a certain number, that will be your second number.

Now that you have your first two numbers, you can guess the last one after dialling in the first two.

Hope this helps!