A passage that feels unreliable often contains a smaller point of friction. It might be a leap, a hand change, a fingering choice, or the moment the rhythm shifts. Find the first place the passage stops feeling comfortable rather than repeatedly restarting at the beginning.

Make the task small enough to succeed. Slow the tempo, use a comfortable rhythm pattern, or practise the hands separately if that helps you hear what is happening. Keep your attention on relaxed movement as well as correct notes.

Then widen the frame. Include the bar before and after your focus area so the new work belongs to the phrase. A good stopping point is one confident, unhurried run—not a target number of repetitions.