Fixes, as a piano

TUNES

Adjusting its pitch ensures every note plays in perfect harmony.

The word "fixes" here doesn’t mean repairing something broken—it’s hinting at adjusting or fine-tuning. "As a piano" points to the action of making small changes to improve its sound, which is called tuning. So "tunes" fits because it’s the verb for that process, playing on the double meaning of "fixes" as both mending and adjusting. The answer is straightforward once you realize it’s about maintenance, not repairs.