Since I posted the key information, several people have emailed saying their
ignition key also opens the gas cap.  Here's the story.  The body of the gas
cap is plastic.  After a few years, the wafers in the lock wear grooves in
the plastic body.  In reality, most any thing that will fit in the key slot
will then turn the lock.  There is no way to repair the caps.  Once they are
together they cannot be disassembled.  Hope this explains.
Steve Sandlin
www.steveslockshop.com
'84 Wolfsburg Westy
'79 Transporter
'00 New Beetle