The Puzzling Puzzle

This is one of our Melissa & Doug puzzles. As you can see the object of this particular puzzle is to experiment with different kinds of locks. The one on the upper right hand side is a combination lock and it came with and easy code: 1-2-3. But once you open it, it allows for you to change the combination if you so desire. So at one point in time this is what I did. Then a lot of time passed and we forgot the current combination.

The puzzle has recently been resurrected into circulation and Jacob really wants to open the one in the upper right hand corner. There are three different one digit numbers that make up the combination. Simple math brings you to the follow equation: 10x10x10 = 1,000 possibilities. That's a lot of trying to figure out the mysterious combination but I am determined. I'm going through systematically, starting with 0-0-0, 0-0-1, 0-0-2 and so on. I spent more time on it this weekend than I'm willing to admit. I actually had to start over at one point because I realized that I also can't remember which way you need to push the little knob over to get it to open once you've got it set to the right combination. So I'd only been doing it one way and what if that was the wrong way?

A girl can only take so much of this monotonous combination testing so occasionally Jacob takes over, but his method is more in line with what you would expect from a little boy. He wants to pry it open with different objects and simply bust the thing into obedience. I try to explain to him that this is not the way because even though it will be open, it will then be broken and we will never be able to figure out the combination. That would possibly be one of the great tragedies of my life. So for now I'm putting up with the monotony in the hopes that one of the combos will work.

I've left off in the 3-7-0 range so I've got a lot of work ahead of me. 10 bucks to the person who guesses what it is.