Locking gas cap

Hello my 80 is 1000 locking gas cap won't open. The last time I filled my tank the locking lever completely  pop out. So I slid  it back in. Tried to refuel and the key just spins. I tried holding the tank on its nose push down on the cap hoping the lever would slide out after taping the tank on its nose.  No go. Any idea's or just drill the lock out . Thanks by  the way it's a  A4

Drive the roll pin on the back out with a small punch or 8d nail flattened on the end. 

Thanks for the tip. It came out very easy. Had the bike since new. The 
2 screws holding the latching mechanism got lose and made it fail. Put all the  springs in the right spots put together works fine.
one screw is striped out have a new one coming from Z1. Thanks again.