No Park lights (help)

Not sure how to help.........you seem to have it isolated, just make sure you are not leading yourself down the "wrong road." Example, a bad connection.........if you are measuring power at the bulkhead with it disconnected, and then connect it up, the loading of the circuit may be knocking the power down through a bad connection. So you need to measure/ test with everything connected as normal.

You sure you have the right terminal at the bulkhead?

Probably the biggest things are poor grounding, bulbs, and since it was painted, maybe overspray, like in sockets, etc.