1991 Subie Vanagon GL

The top screw that hold the latch to the door keeps coming loose allowing the
latch mechanism to rotate around the bottom screw.  It is not clear from the
diagrams in Bentley if these screws have nuts behind them or go into tapped
holes in the door frame.  If they go into holes that are trapped, what is the
procedure for repairing the threads.

Thank you very much,

John