Headlight goes up. Won't go back down., What is broken here? Options

[VegasRacer]

Both headlights pop up as the German engineers intended. Only the left one returns to the down position with the dashboard knob. The right one will go down using the knob on be back of the motor.
What is causing this malfunction? (IMG:style_emoticons/default/confused24.gif)
There are no obstructions. The usual suspect pivot is intact.
Is this a sign the headlight motor is going bad?

[GeorgeKopf]

I am in the middle of refurbishing my headlight motors and I have them all apart.

I'll add pictures when I get a chance.

The motor turns a screw gear that meshes with a round gear. On the face of the round gear is a conductive metal plate. On the inside of the mechanism are three electric pickups.

On the four motors that I have taken apart, the problems seem to be:

1. Corrosion on the conductive metal plate interfering with the pickups.
2. Corrosion on the motor's spindle bearing for the screw gear.
3. Frayed wires entering the motor's body.

Your symptoms sound, to me, like corrosion on the round gear's conductive metal plate.

George