This is a resistor board. The left 2 resistors controls one pair of flash bulbs. The right 2 resistors control a different pair of bulbs. Check the larger resistors with an ohm meter, they should read @5 ohms.

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There are 8 1251 bulbs in this game.

Do you have a voltmeter?

We can start with these. The resistor boards for the topper are right below the topper in the backbox. If you put your voltmeter on DC voltage and place the black lead on the ground terminal of the resistor board and the red lead on the lamp terminal you should read @ 28 volts DC. This tells you that there is power and the bulbs are good. Then move the red lead to the driver terminal and you should read voltage again. This tells you that the large resistor is good. Do this to both sides of each resistor board in the backbox. Let me know what you find.

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I think that is #7 flasher. Look under the play field below the lamp for a resistor board with a white/violet wire on it.