opening the safe

We recently acquired an old Mosler, Bahmann, & Co safe from a friend. We have the combination, but it does not work like a current safe. It gives 4 left then a number, then 3 right then a number and 2 left then a number, we can not open it. Any suggestions would be greatly appreciated. Thank you. PS: There is no zero, it starts at 20 & goes to 100. There is a star and a slash. When you line the slash up with the 20, the star appears to be were zero would be. We are perplexed.