It could also be that the pedal bearings have loosened up. Does that pedal wobble around if you grab it? Otherwise likely to be a worn cleat - ATAC cleats wear out reasonably quickly as they're made of brass.
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It could also be that the pedal bearings have loosened up. Does that pedal wobble around if you grab it? Otherwise likely to be a worn cleat - ATAC cleats wear out reasonably quickly as they're made of brass.