The click that wasn't there

Dan is the one who can fix an engine, and who built a go-kart and a mini bike out of junkyard parts. Matt debugs software. Years ago Dan walked Matt through fixing a lawnmower over the phone by asking what it sounded like — and that turned out to be the whole method. Listen first. The machine tells you what's wrong if you let it finish its sentence.

When we pulled the Bursting Cherry out of seventeen years of storage, it wouldn't pay. Neither of us opened a manual. We pulled the handle a few times and both had the same thought: the song was ending a beat early. There's a click at the end of a good pull — everything snapping back home — and we both remembered that click from years of playing it, and it wasn't there. So we traced backwards from the missing sound. Where does the quarter go? What moves, in what order? What moved last before the silence?

We stuck a screwdriver in to hold the clock from winding down, which froze the machine mid-cycle. With time stopped we could set the reels by hand to any combination and let the payout logic run against it — a breakpoint, or pulling a plug wire to isolate a cylinder. That's when we saw the machine for what it is: three punched metal discs behind the reels, a row of hammers that either drop into a hole or don't, and a payout that only fires when the right hammers all drop together. We also learned that old operators used to plug a hole with solder so a combination would show a win and quietly not pay. Worth checking every disc for.

The culprits turned out to be the quarters. Gunky old ones were leaving residue in slides that are supposed to run bone dry, and brand-new sharp-edged ones were catching where worn ones glide. Chapter 5.

The method, in three lines:

• Listen before you look, look before you touch, touch before you unbolt.
• Everything in this machine is a flow — coins, energy, time, information. Find where the flow stops matching what it should be.
• Don't adjust anything until you can say out loud why it's doing what it's doing. If you can't explain it, you haven't found it.