The debugging reference sheet

This is the chapter to open when the machine misbehaves. Everything later in the book exists to make this chapter make sense.

1.1 The method

flowchart TD
    A[Something's wrong] --> B[Run 5 plays. Don't fix. Listen.]
    B --> C[Which beat of the song is missing, early, late, or wrong?]
    C --> D[Trace the quarter: where does it actually go?]
    D --> E[Trace the motion: what moved, what didn't, in what order?]
    E --> F[Name the subsystem — §1.3 tells you which]
    F --> G{Can you reproduce it on demand?}
    G -->|No| H[Freeze the clock §1.4 and set it up by hand]
    G -->|Yes| I[Compare the bad part to its siblings §6.2]
    H --> I
    I --> J[Say out loud why it's doing this]
    J --> K{Explanation holds up?}
    K -->|No| B
    K -->|Yes| L[Photograph the geometry. THEN fix one thing.]
    L --> M[Re-test. One change per test.]

1.2 The song: what a healthy cycle sounds like

Learn this by ear. It's the fastest diagnostic in the book.

If you hear the song end early, the missing beat tells you where to look. If a beat is dull instead of crisp, that's a weak spring or gum (Chapter 4). If a beat is extra — a rattle that shouldn't be there — something's loose or a coin is where it shouldn't be.

1.3 Symptom → where to look

1.4 The screwdriver trick, formalized: setting a breakpoint

What we did instinctively is a real technique. The clock is the thing that drives the machine forward through the cycle. Hold it, and time stops. Everything downstream waits.

flowchart LR
    A[Pull handle, let reels spin] --> B[Block the clock before it releases the stops]
    B --> C[Machine frozen mid-cycle]
    C --> D[Turn the reels by hand to any combination]
    D --> E[Release the clock]
    E --> F[Stops drop, hammers read the discs, payout runs against YOUR combination]

What this gives you:

• Any win on demand, without waiting for the odds.
• A direct view of which hammer enters which hole, for any combination.
• A clean way to test "does BAR BAR BAR actually reach the jackpot lever" without a hundred pulls.
• A way to test near-misses (cherry / lemon / cherry) and confirm they don't pay.

Rules for the breakpoint:

• Block the clock gently. It's a governed gear train, not a crankshaft. Don't jam it against its own spring.
• Note where you blocked it, so you can put the breakpoint in the same place every time.
• Never turn a reel against its brake or stop lever. Lift the stop, then turn.
• Reproducibility first: same breakpoint, same combination, same observation, three times, before you believe it.

1.5 The one-page decision tree

flowchart TD
    A[Problem] --> B{Quarter reaches the escalator?}
    B -->|No| C[Coin head / entry chute / the quarter itself]
    B -->|Yes| D{Handle unlocks?}
    D -->|No| E[Detector / handle lock]
    D -->|Yes| F{Quarter ends up in the right place?}
    F -->|No| G[Routing: tube shutoff, diverter, deflector]
    F -->|Yes| H{Handle completes the stroke and returns?}
    H -->|No| I[Operating fork / reset]
    H -->|Yes| J{All three reels spin?}
    J -->|No| K[Kicker / pawls / brakes]
    J -->|Yes| L{Reels stop one-two-three?}
    L -->|No| M[Clock / stop levers]
    L -->|Yes| N{Correct hammers drop for the symbols showing?}
    N -->|No| O[Discs / hammers / plugged holes / spacers]
    N -->|Yes| P{Right number of quarters paid?}
    P -->|No| Q[Slides / tube / quarters]
    P -->|Yes| R{BAR BAR BAR dumps the jackpot?}
    R -->|No| S[Handshake / latch]
    R -->|Yes| T{Everything resets? Last click present?}
    T -->|No| U[Reset springs and linkages]
    T -->|Yes| V[She's healthy. Play it.]

1.6 The three rules before you touch a tool

1. Photograph the geometry first. Screw heads, thread count showing, lever positions. A bent-looking lever is often bent on purpose.
2. One change per test. Two changes and you've learned nothing.
3. Dry is the default. If the fix you're reaching for is oil, stop and ask whether the real fix is cleaning. Nine times out of ten on a machine this old, it is.

1.7 Our baseline: what healthy looks like on THIS machine

Measured from VID-01 (Dan's pull, rear view, 30 fps, no win). When something feels off, compare against this.

How to use it: film a pull from the back, count frames or use a stopwatch. If the first stop comes much sooner than a second, or the gaps between stops bunch up or stretch, it's the clock (§3.4). If the gaps are fine but one reel is off, it's that reel's stop lever or spring (§4.1). If the timing is fine and it still won't pay, the clock is innocent — go to the reader and slides (§3.5–3.6).

FILL IN: a second pull filmed at 120 fps from the same spot, and one filmed on a winning combination (use the breakpoint to set it up) so we can baseline the slide stroke and the payout beat too. → Chapter 7.