Did they work correctly when you replaced the motor originally? If so:
95% chance that when you put one of the lights back on, the actuator arm didn't get on the motor shaft correctly, isn't seated all the way down, and its not engaging the stop correctly. (Watch the good light and how the arm rotates around to hit the metal stop. The other side should do the same.)
Black 1999 Firebird Formula WS6; M6
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