Seems obvious, but since no one mentioned it, don't forget to check the interlock switch as the AC voltage for the flashers from the transformer goes through the coin door interlock switch. You can always back probe the connector across the two WHT-RED wires on the connector coming from transformer to see if you have voltage there.
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You can also completely bypass the interlock switch and its wiring by connecting the PDB directly to the transformer secondary's by making the connection shown below:
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Correct, with the exception of GI lighting the transformer winding are NOT bonded to ground anywhere so there is no difference between holding the second meter lead on ground than there would be holding it in open air when making the measurement.

Assuming the replacement Bridge was had the same specs as the original, I would lean more towards a broken connection point over a second failed Bridge Rectifier.