I noticed that DBB interface was on, PeterK and I went to the floor to turn it off.
For locking DBB PMC, it uses a 1MHz oscillator of some sort (probably just a canned crystal). The oscillator is ON all the time even when modulation is disabled as far as it is powered but its frequency is not monitored.
I think the oscillator is from auris, part number O-1.000000M-AQO 14-50-5.0-A. It's a little difficult to tell from the schematics.