After you get to the back office you will need to fix the machine so that it shows 324.
This is the low-spoiler guide for "Fix the number display" puzzle in The Darkside Detective - A Fumble in the Dark. Unlike in normal walkthrough, you get gradual hints on how to solve the puzzle. Click the big button below to see your first hint. If the hint contains a spoiler, you will be warned about it before clicking.