Chris,
     First see if you have the round plastic cap on the outside of the arm.
If you do, pry it off and remove the allen bolt below it.  The arm will slide
off, revealing 2 smaller allen screws behind it.  Tighten them and use
Loc-Tite to keep them in place (prevent it from happening again).  Replace
arm and the big allen bolt, but don't over tighten it - then you can't move
the arm!  Use loctite and just snug the bolt, checking as you go to see if
the arm moves satisfactorily.  If you don't have the plastic cap, follow
everyone else's directions about driving out pins, etc.

Bill Marshall
85 GL Tiico
Phoenix AZ