I've got a doorbell that works, it is the normal two chime "ding dong", but it goes "ding chunk" where the second chime seems muted. I looked at it and it's mounted right, it gets hit with enough force. What would cause this?
Turns out that there was an intereference hitting into it--the cord coming into the doorbell box "from the wall" was bent up and barely touching the chime bar. So bent it down a little and working doorbell again.