When removing the non working factory alarm I had the glove box et al out, the connections to the alarm unit behind the glove box were rusted badly. I followed the water trail upwards and it was the lower left corner of the screen leaking. I had the screen removed an replaced with a new rubber.
Left the glove box out, sprinkled everything with talcum powder and then hit it hard with the hose pipe no more leaks....yet.
regards
Dave