They all break.

I chopped the remains out of my hinge and installed an auxiliary ground wire. I found a convenient spot on a strut under the headliner -- it either already had a hole or I drilled one (and sanded off the paint). I ran a wire from there, through the hinge, into the tailgate, and attached it to a bolt for the wiper motor bracket (or similar).

Eye terminals crimped at ends of the wire.

For wire, find some instrument test lead wire. Radio Shack should have it. This wire is highly stranded (so it can resist a zillion flexes without breaking) and the insulation (rubber) is super flexible, so it will bend in the cold.

The Radio Shack wire probably has the less desirable plastic insulation -- if you can find an electronics supplier, get good test lead wire with rubber insulation.
--
Don Foster (near Cape Cod, MA)