Hello all, first time poster here! I am currently replacing switches in our 1920 1.5 story Kentucky home. I have run into what appears to be a 3-way switch, it is round and has "reed" like contacts inside. The switch is operated by turning 90*. My fluke multimeter shows 120VAC on one lead and nothing on the other 2..... Onto my question- how do I wire my new 3-way switch???