I have both the mark 6 and mark 7 models. They are grounded to 8 foot electrical ground rods. The fence wires are touching nothing but the insulators but they wont send a current through the fence wire. When I take the leads loose from them they peg out on voltage output but when I hook them back up, same thing, no voltage on the fence. Awhile back I accidentally got my leg up against the ground rod on one of them and it knocked the bejabbers out of me! They worked fine for the first yr or so the way I have them set up and I never had a problem. For the last few months though they have been acting up the way I have described and I don't know what the heck to do about it. Any input you may have about this problem would be greatly appreciated.