1. Remove the nut on the outer end of the power unit where the mast comes out of the car and remove the antenna mast.

     3. Put the power unit on the bench and remove the cover.

Now take note of the washer between the cover and drum, remove it.

With the washer out of the way, grab the drum and remove it.
 

Now remove the cover for the main Gear.   This will expose the main gear.
  

Now pull out the main gear.
  

Now find the roller.  Pull it out and inspect and make sure it is Ok.  If the roller is bad, other than finding a used one out of a salvage power unit there is no fixing this problem.
    

This is how a good gear and roller is to look like.