My alarm goes off if I lock the Beetle.

My burglar alarm goes off when I lock the Beetle. It either goes off within a few minutes or later - hours later. The only way it won't go off is if I leave the driver's door unlocked and lock the passenger door from the inside. I believe it is the micro switch in the passenger door. Ever since the window broke and was replaced I've had the issue. I need to know what to order and how to replace it.