It's very difficult to isolate headlight gearbox problems without partial disassemble. The photo below shows what usually goes wrong with the gearbox. The rollers deteriorate and crumble. The picture shows why you probably need a roller kit. The pile of plastic pieces in the lower right is ground up rollers. Other parts of the picture show where the rollers go in the assembly.


Another common problem with the headlights is the bellcrank that mounts on the outside of the gearbox tends to round out the flats in the  mounting hole. Below is a picture of original bellcranks. Note condition of each of the mounting holes. The far right is is completely rounded out in the center and will need replacing.


Some people have reported good results by tightening the nut on the bellcrank when the hole is just worn like the one shown in the center of the photo above. I recommend replacing worn bellcranks for trouble free operation.

Several people sell replacement steel bellcranks.  As you can see in the photo below the bellcrank in Barney Eaton's kit is superior to the stock bellcranks.   You will need two kits to repair both headlight gear boxes.

Replace rollers at the same time you replace the bellcrank to avoid future problems!