Quoted from insx:
My top Sandman arrow and the Sandman flasher are not working. It seems odd that these are the only two lights not working but the wiring at the holders look OK. Is there any weird reason for this or is it just normal lamp/flasher diagnostics at this point?
If LEDs, make sure the little wires on the plastic end are turned out a bit.
Otherwise, for the controlled light, look at the lamp matrix and follow the two wires to other lights on the row and on the column and make sure that the wire didn't break off on the upstream wire from either the row or column.
For the flasher, also check the wires from the other flashers to ensure the wire did not break at an upstream flasher.
Just for sanity check, if above does not work, you went into the all lamp test and the top arrow is the only one not working? Same for testing the flashers?