I opened my playfield to get the third shot. Thinking you mean the white button switch that tells the pin that the coin door is closed.

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Looking at several other Dr Who pinball coin doors, it depends what door you have. The 2nd and 3rd pictures are mine and I think it is a later door than came with the machine, based on the date on the sticker. But the interlock mount is part of the door, in the top right corner (looking from inside). Picture 1 above, is from another machine that looks like it has an add on interlock plate. (as seen in Marcos site: https://www.marcospecialties.com)

Operators, from what I have read, changed doors. The dollar accepting ones were an option at one point. Your door looks very new. Notice how the 4 test switches are closer to the door opening. I see that you have the bracket and and 2 lug switch. I also see the two pink plugs that attach to your switch. Looks like all you are missing are a couple 3/8 wood screws to attach the switch. Are there two holes in the cabinet that line up with the bracket holes? Alternatively, you could just jumper wire between those two pink plugs and never worry about the "Open Door" warning message. LOL.

So looking on Marcos web page for replacement coin doors, I think I found yours. It says it is compatible with Dr. Who Machine. The first picture I posted was from when a Dr. Who was first delivered. You and I do not have that door.

COIN DOOR ASSEMBLY ENTROPY 2 CHUTE WPC HARNESS
#09-61000-X
New Entropy brand Williams/Bally WPC system standard 2 chute Coin Door used on all domestic late model Williams / Bally pinball machines.

Includes 4 button Service Switch assembly, coin mechanism wiring harness, coin microswitch, and lock with 2 keys. Coin mechanism and bill acceptor wiring harness not included

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