It is a 50 year old machine you idiot - It is going to make some noise.

Seriously. It is. On these EMs things like flippers, alternating relays, hold relays, lock relays all make noise. Some more than others. Sometimes you can make the buzzing go away temporarily by pushing on the frame of the relay making the noise. I'm even working on someone's game where the game over/latch relay makes a horrible noise. They even tried isolating the frame from the wood with rubber washers. Doesn't help.

Get the game to the point where it's making the noise. Open the coin door, remove the lockdown bar, remove the glass, remove the ball and lift the playfield. Find out which relay it is. Push on the relay frame and see if it gets better. Turn game off tighten the screws holding the relay down and maybe clean the contacts on the relay. Honestly not much you can do beyond that. But you might get lucky and tightening the screws that holds the relay down or moving it's position slightly makes it better. Don't be surprised if it comes back.

Sometimes an Alternating relay will do that on Gottlieb games, but this is Williams so what you'll have to do is stick your head in and track it down.

Check what Clay has to say: http://www.pinrepair.com/em/index3.htm#buzz

Lift the playfield and start a game. You should be able to point it out real quick. My Central Park has a hold relay that stays energized until the first score is registered.

On Williams relays, I've found that blades of the switches can be over adjusted and that can act as sort of an over tensioned return spring on the relay, making the switch harder for it to pull in and cause a buzz. Also as others have said, the frame could be slightly out of spec/ bent. Look at the paper on the relay coil, is it darkened like it's been hot? If so, replacing the coil will likely solve the issue. You can also try folding a piece of 200-300 grit sand paper to just fit between where the coil makes contact with the plate it pulls when energized, and give it a few pulls through there to clean the surfaces up where they meet. There are several reasons coils get noisy, these are what I can think of off the top of my head.

Buzzing can be caused by a number of things. The armature plate may be dirty or worn, The spring tension on the plate may be too high. The leaf switches themselves may be pulling with too much tension. Replacing the coils might help...might not.

Thought I would mention. Out of literally hundreds of machines, here's how many coils I've had to replace due to buzzing.

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Probably not. Coils don't make noise directly but they do make noise indirectly by vibrating a baseplate or something else connected to them. What will probably happen is that taking the assembly apart to replace the coil and putting it back together may correct whatever is loose or misaligned. If the coil pulls in the actuator there's nothing wrong with it. But I understand the psychology of buying a new coil to fix the issue.

Try to locate the source of the buzzing first, many times a slight adjustment of the metal armature is all you need.

The metal base plate, the actuator plate that pulls in to move the switch stack, the spring tension, etc can all cause the buzzing. There typically is a metal piece that can be bent to move the actuator plate closer and father away from the coil that can be adjusted too.

I have quite a few relays that buzz during certain times. It's the nature of the beast on AC coils. You're not going to get them to be super quiet.

When pressing on it makes it quieter, that suggest that there is too much tension pulling the plate back. This could be caused by too much tension from the armature spring. The other thing is the amount of tension being applied by the leaf switches. Especially the one in your first photo. It has six switches. You may have to adjust all of them to reduce the tension. I've seen some that will actually work with no armature spring attached. Just the tension from the switches was enough for them to spring back.

I've also seen lock relay coils that had the wrappers burnt to a crisp (like yours) and they still worked fine with no more buzz than normal.

Here's what I'd do. Game off. Desolder the green wire on the lock relay coil lug and tape the end of the green wire you just desoldered. Take a thin piece of stiff paper and slide it between the contacts of the switch at the lock coil. Turn the game on and play a few games. Does it play the same? Does it sound different?

Looking at the schematic, that lock coil is energized as soon as you turn the game on and it opens that contact and stays open when the game is on. Turn the game off, and that contact closes.

The lights are on a completely separate circuit. Shorted socket or old fuse. Fuses can go open without being in an overload or short circuit condition. Make sure there are no lamp sockets close to any other pieces of metal that can cause a short from vibration.