I have not dealt with the situation myself, but I have found this homemade conductive glue has worked pretty well on some broken electrical components (not so sure though how it might stand up to vibration):
I use a Power Antenna which can be found on Evilbay. I have them in 2 cars and they work great. Whatever you do don't drill a hole in the body to put in an external one. Try this or the method with the conductive glue.