Agree with the Rev and adding a possible intermittent connection that riding vibrations help reseat. COnsidering it is an '83 all sort of possibilities fore wiring gremlins.
May 19, 2014 11:03 AM PDT
Pull the lens covers, clean the bulb sockets with isoprophyl alcohol then apply a light coating of electrical grease. This should fix your problem.
Thanks guys!
June 28, 2014 11:47 PM PDT
Got to agree with everything so far, Corrodided bulb socket, mositure, blubs going bad the vibration resets the bulbs.