One other thing - I can't find the post I made about this, but I sent a pic of the guts of my 2565 HK asking what the silver box by the bell was.

Ed answered back it was a buzzer - but there was a fair amount of debate about what voltages it was compatible with.

I used orange/yellow instead of green/yellow for buzzers this time. Turns out the "silver box" was hooked to orange/yellow.

Works great at 18vac. In fact I was pretty shocked at first, as I hadn't installed a buzzer in it yet... and here it was, buzzing away.