Zen and the Art of Slot Machine Maintenance
Chapter 88

Our machine: the living record

what we know so far

Everything here is specific to this machine. Blanks are things we haven't looked at yet.

8.1 Identification

Cabinet serial:                   OPEN
Serial location / photo:          OPEN
Front casting numbers:            OPEN
Chassis stamps:                   "P 2" / "C B…" seen on casting right of reel 2 (IMG-02) — close-up needed
Mechanism family:                 OPEN
Handle / escalator / clock style: OPEN
Slides in the stack:              six, vertical: A2 B3 C4 D4 E5 F2 (OURS)
Stops per reel:                   OPEN
Signs of mixed or replaced parts: OPEN

8.2 What we know

Fact How we know
Mills Novelty Co. Bursting Cherry, circa 1937 model literature
Casting right of reel 2 is stamped "P 2" with "C B…" below it IMG-02 — needs close-up
Reel strips: Bell-Fruit-Gum / Mills Novelty Co. Chicago / Copyright 1910 text, matched print on all three. The Bell-Fruit-Gum logo is the BAR symbol IMG-01, IMG-02
Three code discs, one per reel, each with multiple holes OURS
Payout slide stack at lower left of chassis (rear view), each slide with its own return spring. Six slides, vertical, holding 2/3/4/4/5/2 quarters top to bottom = 20 IMG-02, OURS
Clock / governor gear train at lower right (rear view) — this is what the screwdriver holds IMG-02
Big diagonal extension spring on the fork = fork return; stretches nearly flat on the stroke, snaps back IMG-02, VID-01
Tall coil spring on a hooked rod at right (rear view) — likely handle/reset return, VERIFY IMG-01, IMG-02
Cash box: metal drawer on the wood shelf directly below the chassis IMG-02
Rear view mirrors the reels: reel 1 is on the image right VID-01
Stop timing: first stop ~1.2 s after the kicker, then ~0.7 s and ~0.6 s between stops VID-01 → §1.7
25¢ play OURS
Award card is the standard Mills bell card: BAR×3 = 20; Bell×3 or Bell-Bell-BAR = 18; Plum = 14; Orange = 10; Cherry-Cherry-Lemon or -Bell = 5; Cherry-Cherry-any = 3. No separate jackpot line printed IMG-03
Three coin destinations: cash box, payout tube, jackpot/bonus chamber OURS
The jackpot is progressive. It does not get a quarter every play and does not fill before the cash box takes coins — a share of coins goes to it while the cash box is already collecting. The Mills-literature cascade model does not apply to this machine. OURS
Which plays feed the vault looks random from the outside, and the vault takes a long time to fill — so the share is small OURS — years of watching it
Big diamond-shaped center front assembly OURS
Clock can be held with a screwdriver to freeze the cycle; reels can then be set by hand and payouts triggered OURS — our breakpoint technique
Reader is hammers-and-holes on code discs OURS — seen it
Missing last click = reset not completing OURS — our first bug
Gunky quarters foul the dry slides; sharp new quarters jam OURS — root cause of the first bug
Unidentified horizontal cylinder outside the chassis, lower left in rear view IMG-02 — VERIFY

8.3 Capacities

Till (payout tube) capacity:         OPEN
Primary jackpot capacity:            OPEN
Reserve capacity (if any):           OPEN
Vault fill ratio (1 coin in N?):     OPEN — small; fills slowly; looks random
Splitter mechanism (counter / condition): OPEN

8.4 Verified award table

Card transcribed from IMG-03 — see §3.6. It's the standard Mills bell card: 3 / 5 / 5 / 10 / 10 / 14 / 14 / 18 / 18 / 20. What's still open is the hammer-by-hammer verification (§7.5): confirming each row actually pays what the card says, and what BAR BAR BAR does beyond the 20.

8.5 The vault — open questions

  1. One chamber, or primary + reserve?
  2. Which one shows from the front?
  3. What's behind the big center cherry diamond — chamber, display, both?
  4. Does it hold quarters? Trap door?
  5. Which chassis linkage reaches it, and which combination fires it?
  6. Does BAR BAR BAR release it? Does any other combination release something else?
  7. Does BAR BAR BAR also meter 20 from the till?
  8. How many cycles for primary relatch → reserve transfer → reserve re-close?
  9. What exact part causes till overflow, and what exact part is the splitter that decides vault vs. cash box?
  10. Is the split a counter (every Nth coin) or a condition (certain plays only)? What's the ratio?

8.6 Bug log

Date Symptom Level reached Root cause Fix Result
(before v4) Not paying; last click missing 2 (clock frozen, reels set by hand) Gunky quarters fouling dry slides + sharp new quarters jamming; reset incomplete Clean coins & slides; feed worn quarters Paying — confirm and record

8.7 Registers

Spring, fastener, adjustment and part registers live in the Appendix.