To the best of my knowledge, the original idea for Trouble Clef comes from Europe. We at Livewire Puzzles were introduced to it by Howard Swift, one of the best-known wire puzzlers in North America.
If you know wire puzzles you should be familiar with the underlying principle behind Trouble Clef. That's what I thought. The trick is to take what you know and apply it here. Trouble Clef requires a twist in your thinking that makes it much more difficult to solve than one would expect. For yet more reasons, which I'll leave for you to discover, Trouble Clef certainly deserves the "toughest-of-the-lot" spot in our current puzzle lineup.
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