It seems to trigger when the garage door is opened or closed, there is no sensor or keypad nearby, however the outside alarm siren/light box is mounted nearby so suspect the vibrations of the door might be upsetting something?
I have pulled the cover off, confirmed no moisture or bugs have got in there, and checked all wiring is firmly connected, and given it a blow out of dust and cobwebs. The tamper switch inside the siren box seems to switch on/off with a nice positive action, and I can hear it clicking on when I replace the cover. Can't see any damage or deterioration on the components but have not individually tested them (that's grasping at the limits of my knowledge)
Any suggestions? or is it time to call in the experts and shell out some hard earned $$$ (Damn!!!)