When all else fails read the POH/ AFM
The fun way to check it is to get in slow flight and play a tune on it .
I flew with an inspector of twenty five years experience, who had never played a tune on the stall horn . We had some fun doing that . I can still see his face light up as he played a tune . I think the lesson was how to help someone having difficulty landing and I find that most students that have difficulty landing have not had enough practice or confidence in slow flight regime of flight .