On Fri, 19 Feb 2010 14:59:46 -0800, Kate wrote:

Do you have a voltmeter that you can use to check if the transformer
is putting out 16 -24 Volts AC?
No, but I have a friend who does. I will know more in about a week,
when he is here. Thanks.

Send him a note to remember to bring the meter. Check the wires at
each location. If the transformer is bad or a wire is broken - check
them both. Some doorbell wires have multi-pairs of wire (old phone
line or CAT-5 type). If one wire is broken, swap out another color
pair...

Good luck!