R.E.A.L. · Discovery

It Worked Yesterday Change-Window Worksheet

A structured worksheet for capturing the change window when everyone knows it worked before, but nobody knows what changed.

Walt — Simple Man Takeaway

There was a point when it worked and a point when it stopped. The answer is hiding between those two points.

Walt says STOP! - Safety First

Make these checks prior to proceeding.

Do not use discovery as an excuse to bypass energy control, guards, procedures, or human judgment. If the live condition can hurt someone, stop and make the condition safe first.

Guided Flow

Check each step as you work. This is a first-check flow, not a replacement for lockout/tagout, OEM procedures, qualified authority, or site rules.

1. Define Point A

Describe the last known good condition.

  • When did it run correctly?
  • What product, speed, operator, recipe, tooling, environment?
  • Who saw it working?

2. Define Point B

Describe the first known bad condition.

  • When did it first fail?
  • What was the first symptom?
  • Who saw it fail?
  • Was the visible fault the first bad movement?

3. List people changes

Capture human/process changes without blame.

  • Shift change, new operator, training, fatigue, pace, supervision, maintenance handoff, changed instruction.

4. List product/material changes

Capture what the machine is handling.

  • Supplier, batch, size, weight, gloss, moisture, label, stiffness, burr, temperature, packaging.

5. List machine changes

Capture adjustments and physical work.

  • Tooling, guide, sensor, belt, chain, bearing, valve, cylinder, drive, program, replacement part, cleaning.

6. List energy/environment changes

Capture the surroundings.

  • Air pressure, voltage, lighting, temperature, humidity, dust, water, oil, curtains, welding, forklifts, vibration.

7. Rank probable causes

Do not chase everything equally.

  • Which change best matches the failure window?
  • Which is easiest to verify read-only?
  • Which check protects evidence?

8. Run one controlled test

Turn the change window into learning.

  • Test one variable.
  • Record result.
  • Keep, reverse, or escalate based on evidence.

Discovery Questions

What changed?Use the change window before altering the machine.
What is the first bad movement?Do not let the visible symptom hide the starting point.
What can be captured read-only?Preserve the truth window before changing settings.
What is one safe controlled adjustment?Make one change, observe, and learn.

When to Arm Ghost Busting™

The change-window worksheet helps identify where the ghost may live. Once the suspect stage, circuit, station, or sequence step is narrowed, enable Ghost Busting™ as the read-only digital twin comparator.

Manual discovery chooses the trap location. Ghost Busting™ captures the evidence.

  • Pick the cycle stage where the first bad movement appears.
  • Define expected behavior for that stage.
  • Mirror the live circuit/process at the edge.
  • Compare expected vs. actual every scan.
  • Lock context when the mismatch appears.

Related Pages and Tools

Boundary

This flow is practical field guidance. It is not OEM procedure, safety approval, engineering sign-off, lockout/tagout instruction, or permission to bypass guards, interlocks, or qualified authority. Humans remain the authoritative part of the machine.