Okay, I'm going to assume this is true and your 3 lane lamps at the top of the machine are working.

I personally like to check the simple stuff first...the Yellow-Orange column wire feeds thru the 3 lanes board connector, the lamp harness will connect from the PDB to the lanes first, then proceed down to the Multiplier board, it's a free check to take a look at that, or just simply measure continuity from J137-3 to the Yellow-Orange wire on the lamp board.
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Edit: Lamp columns could be on either on J137 or J138 and the manual has conflicting information on this...in reality it shouldnt matter which one its connect to as they are electrically identical, this actually makes it easier to check as you can use the pins of the unused connector as test points
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If you cant fix it with this information, my standard repair fee is $95/hr plus parts; the clock starts when I get in my car and ends when I get back home