Getting in without tearing down
6.1 Three levels of access
Stay at the lowest level that answers the question. Most bugs never need Level 3.
| Level | What's open | What you can do |
|---|---|---|
| 1 — Cabinet open | Back / cash-box door open, chassis still in | Watch the mechanism during a real play; trace quarters to their exits; see the cabinet side of the jackpot handshake |
| 2 — Chassis out, intact | Mechanism on the bench, nothing unpinned | Hand-cycle everything; freeze the clock; see and touch nearly every spring; sibling comparisons; measure in place; film slow-mo. This is where 90% of diagnosis happens. |
| 3 — Subassembly off | Something actually unbolted | Only after Levels 1–2 have pointed at one assembly and it's been photographed per Chapter 7 |
6.2 The Level-2 toolkit
- Hands. Cycle the fork by hand, slowly. Feel for the lump in the cam.
- Ears. The song (§1.2), one beat at a time, at hand speed.
- Screwdriver as breakpoint (§1.4).
- Flashlight, dental mirror, USB borescope.
- Calipers, machinist ruler.
- Small fish or luggage scale, for pulling a spring end to its normal travel and reading the force.
- Phone at 120 fps.
- One marked quarter for tracing routing.