TheGear Puzzle

How it works

1. The victim stands at the centre. Each dancer is a gear that watches through its wedge of red Xs.
2. Turn the crank to set the gears before the dance. Meshed gears turn together, neighbours in opposite directions.
3. Scrub through the dance. At each of the 8 convergences the dancers close in, and the counter shows how many of them see the victim.
4. Only one crank setting and one convergence leave a single dancer watching while everyone else looks away. That dancer is the killer.
5. Leave the crank and the scrubber on that moment, then accuse. The crank, the convergence and the gear must all be right.

Fix the Diagram

1. As printed, the diagram has no moment where exactly one dancer sees the victim.
2. Tap two gears to swap their starting slots, up to the number of adjustments allowed.
3. Only one set of swaps makes the diagram solvable. Then find the crank, the convergence and the killer as usual.