uncooperative lights

[S-13]

I know that my stock headlight motor is still working since they can go up with ease. The problem Im having is my passenger side refuses to go down from either the headlight stalk or dash switch. When I try to manually roll them down by turning the knob above the motor, the motor quickly takes over after being manually lowered a tiny bit and cycles the full down and then full up position again. Is this something that can be repaired or should I resort to buying an assembly from another 240? If that is the case can the driver side and passenger side assemblies be interchangable? Thnx guys