Les,
That's a good idea. I no longer have the manual, but perhaps I can look it up, or figure out how to re-code the transmitter and receiver.
I am leaning towards an issue with the unit though, because of my area. I live in a semi-rural district. I have three neighbors, about 50 to 75 yds (45 - 69 meters) away. That would be a long reach for unit, but possible. Also, it's possible that another device, besides door chime, is sending errant signal, and the other device might be more powerful so it could cover that distance.
Les, as you suggested, if I can change the code, then that might solve it.
Joe