Yeah, you can't test AC like that, as you need to go ACROSS the transformer secondary coil. From the WPC manual you can see that here. Putting a probe on pin 1 with meter set to AC, put the other probe on pin 3,6,9, or 5 (they are all tied to the common point on the other side of the transformer winding) you should see a measurement of your transformer secondary AC. Make some sense?

The diagram below gives an idea, its from the WPC schematics manual, but appears a little different that your transformer setup.

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This is GI voltage, it's only for the lamps.

Switches are in the switch matrix, see page 3-15 of the Hurricane manual - the switches connect to J6, then leave the board at J1 to be trucked over to the CPU board

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The switch in question is the memory protect (#22 in the matrix "Coin Door Closed") GRN/RED col 2 wire in diagram below J6-6

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Well, as Clint said "Man's got to know his limitations"

Pg 3-19

Pg 3-18 is numbered, the next page 3-19 has no number on it, just the lamp and switch matrix diagrams. The switch matrix chart is the bottom one. It's right there in the picture you posted. There's just a couple extra pages on IPDB digital copy online of manual addendments

http://mirror2.ipdb.org/files/1257/Williams_1991_Hurricane_Manual.pdf

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Using the table, find the switch and determine the row and column. There is the information on the wire colors and connector pins that are used to determine switch closures. Grounding the appropriate row and column signals the MPU of the switch closure.

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http://arcarc.xmission.com/Pinball/PDF%20Pinball%20Misc/Williams%20WPC%20DMD%20Schematics%2016-9473.pdf

http://www.pinwiki.com/wiki/index.php?title=Williams_WPC#Direct_Switch_Problems

J205 pin 9 doesn't match what I have for schematics for the direct switches. Pin 9 goes nowhere.

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Ah, yes - I think I need the WPC-89 schematics and I don't see those online.

I would ohm from the connector, to the diodes cathode and then from the diode to the resistor. Check resistor and diode. This confirms the trace isn't damaged anywhere. Then try swapping the LM339s

Good job!

Jumper wires are fine in most cases, when installed to IPC specifications. There are other methods if you can locate the exact break.

https://www.ipc.org/4.0_Knowledge/4.1_Standards/7721Change%201.pdf