I have a ~1975 Eichler and the doorbell doesn't work when the doorbell is pushed. But, sometimes the doorbell sounds by itself. I found the recessed box, covered by a louvre-door in the hallway, that contains the chimes and transformer. As far as I know, the transformer is the original. The transformer has recently started to hum. When I remove the wires that are screwed onto a small plate in this recessed box, there are sometimes sparks. My question is: what is wrong and how do I fix it? I'm guessing that the transformer is not good, but if that were the case, I don't know why the doorbell would occasionally sound on its own. Any ideas on what to do?
I suspect that the wires screwed into the small plate ground the transformer and/or the chimes. If so, removing them while the circuit is live is not a good idea because then the electricity will look for the next possible place to return to ground, i.e. sparks to random places.
It sounds like you may have 2 issues -- (1) your doorbell button switch itself is broken, hence the doorbell won't work when the button is pushed and (2) there is an intermittent short somewhere in the wires between the switch and the chimes/transformer, which causes it to sound by itself once in a while. Both of these should be easy enough to check with a multimeter.