Success! The 60Hz power line lock relay buzz noise was driving me crazy on my Jubilee I tried everything suggested in forums and pinrepair. I figured the only real solution to make it 100% quiet was to convert coil to DC. So I made a small rectifier circuit to drive relay and eliminate buzzing. So for a few dollars the humming is completely eliminated. The machine had 28VAC to drive coils and I measured 37.5mA dissipating near 1 Watt of power. The coil measured 20 Ohms but DC resistance is much different than AC impedance so a large current limiting resistor was going to be required. The best standard value I could find was a 820 Ohm, 5 Watt resistor. This limited the current to 42 mA with relay activated. Unfortunately I could not get the relay to energize on it's own so I then added a 330uF 50V capacitor across resistor. This gave the relay the initial jolt it needed to fully activate.
The 28VAC measured 36VDC after rectification and filtering. If you have a newer EM with higher solenoid voltage you will need a higher voltage rated capacitor.
Here are photos of fix:

UPDATE: While playing the game reset sometimes when solenoids and flipper were active (maybe cold solder joint?). I modified parts to have resistor be 750 Ohms and filter capacitor across bridge +/- to be 1000uF 50V. Now game is 100% reliable. Hope this helps anyone with same annoying issue.

Lock Relay Buzz Fix Wiring (resized).jpgLock Relay Fix Parts (resized).jpg