I live in a very old house. Up until recently, my doorbell worked fine, but at some point in the last couple months it stopped working. At the transformer, I see ~18V, so that appears to be ok, but it is what I see at the chime that has me a little confused.
The previous chime had three unlabeled wires run to it. My working assumption is that 1 is to the transformer, 2 goes to the front door and 3 may have run to another switch (but I don't know where this is/was). This is where I have become stumped: At the chime, if I measure between 1 (the transformer wire) and either of the others, I read ~8V. I get this reading whether the front door switch is opened or closed (I took the button off and have tested Voltage with them loose and also tied together). Can anyone help me with a likely explanation for this? As I said before, the system was working up until recently.