TeamStarlet I've never seen this tool before, very interesting. I do have an observation though. All the locks in the instructions are for locks that have the combination chamber directly contacting the buttons. The 900 locks don't have that. Though the combination chamber is the same, the buttons have varying length "arms" that connect them to the chamber. There is a lot of flex in those parts. Compound this with the assembly method, they are "roll crimped" together, and they ALWAYS become sloppy with use. Replacing those button towers is the main repair on 900 locks. I would really like to try that tool. I have hundreds of Simplex locks at work. Thanks for the lesson!
"All ye who come this art to see / to handle anything must cautious be...." Benjamin Franklin