constant damp weather did the same to mine, started going off whenever it felt like it, then i had to kill it completely after smoking and bubbling siren box got yanked out just before a serious car fire started. it happened outside my local go kart track,i had no tools, must have looked odd,some bloke smashing his engine bay up with a steering lock, but luckily it had enough weight on it to smash the wires out of the siren unit and stop the bubbling plastic from catching, i couldnt just yank the wire as it had no coating left and was very very hot (as i found out when i grabbed it ouch!) .