Harmonic damper installation

pull it off and do some more measuring. If you do enough measuring it should be pretty obvious if the damper is fully seated or not, and how much surface should be exposed. If you want to be absolutely positive, put some Prussian Blue on the inner end of the dampener snout, and see visually if it's contacting shoulder on crank. Definitely, do not operate the engine until you are SURE the dampener is fully seated.
Oh yeah, a Harmonica is sometimes called a mouth organ. If you want to really play a harmonica, you'll try some heavy blipping of the throttle with your hand while stretched over the fan area, and a half-a$$ed installed harmonica dampener, hahaha.