I. Check the costume of the animatronic and make sure that nothing is stuck inside the mechanism, preventing it from returning to rest.
II. Make sure there are no objects obstructing the prop from returning to rest.
III. Ensure that there is no part of the costume stuck in the mechanism preventing it from popping or lowering to rest.
IV. Check for damage to the gear, follow the arm into the mechanism, see if the gear has damage to the teeth or if it snapped and is no longer there.