The octave arm should pivot freely when tapped. The least likely issue to impact the arm's performance is an overly tightened screw that holds the arm and allows it to pivot. If this screw is too tight, it causes the frame the arm sits in to constrict and prevent movement.

Simply loosening the screw a small amount should allow movement. This model used a 2mm flat-head screw. Most models should be the same, but may vary slightly.

The screw should not be removed. It should only be loosened enough to allow for ease of movement.