Thanks for this thread Steve. I'm currently working on my first EM as a repair for someone. A Williams Aztec. Today, I reinstalled the relay/motor board after cleaning and fired it up minus the playfield to test operation. The first thing I noticed after turning it on was the coil hum of the lock relay. I was, too, baffled by why this was on. The coil is in decent shape but it showed more wear than any of the others. It became, of course, very warm. I took notice of this to look up later and was happy I found this thread. Now I see it's normal. Thanks again. FYI, manually scoring the machine worked without issue. Now, on to the playfield.