I'm replacing a doorbell chime unit. The old one worked, but the new one does not. If I connect the wire to the terminal labeled "front", it will ding. If I connect the wire to the terminal labeled "rear", it dongs. The latter makes sense as that should be so a rear or side doorbell has a different sound. But why doesn't it ding-dong when connected to "front"? The hammer moves freely up and down (no wire in the way blocking it).
The transformer measures only 11 volts. That seems low, should I replace it? If not, what else could be the problem?