Cool! I saw 7000’s when. I was on the Red Line to Shady Grove. I took it to Friendship Heights! Then got the 3000 Series back! Which is phasing out to the 8000 Series
That horn is a Nathan Airchime K3HA. Reason why I THINK it might have gotten fouled ether the Manifold might have gotten sore or it had something to do with the cold weather. (Not a huge expert of how Horns get fouled)