On my 1994 XJ6 my drivers door latch can be latched by pressing against the latch plate with a round bar like a large phillips screwdriver but if i then use the same round bar in the engaged latch plate I can pull the latch plate back open again. I tried the same thing on the other doors and this is NOT the case with those other doors. Since this is the drivers door it gets the most use. Is there something inside the latch mechanism that wears out with age and use?