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The Miscoloured Cog 
Shown are sets of cogs on three levels driven by a single compound gear (of the type illustrated above right). The compound cog is not always easy to spot - the stacking can often hide the lower cogs - but its rotation is always in the clockwise direction.
The viewing direction (looking down from above) means all the cogs are projected onto the same plane.
To separate and distinguish the three groups of interlocking cogs, cogs on each level are assigned the same colour.
However, one of the cogs is wrongly coloured. See if you can spot it. The challenge is to find as many as you can in 2 minutes.
The puzzle changes after each click, hence you only have one attempt at each random arrangement of cogs. Click anywhere on the miscoloured cog to make your selection.