Nikon E200, E400, E600 Condenser Pinion.  All Metal Replacement Part.  
#MS1104
 
You no longer have to deal with the tiny snap clip when installing this part.  Use one plastic washer, lubricate the part before installing and tighten the lock nut to set tension so the condenser doesn't drift on it's own.  Simple, one time repair lasts a lifetime. 
 
Original Nikon Part Number #2K380-347