The + connection is via a wire to the battery. The - connection is via the mounting bolts of the jack to the tongue of the trailer. When I installed mine there was a star washer that was placed between the jack mounting plate and the chassis of the trailer. There is a possibility that the connection on your jack has corroded or rusted. Check it out by blocking up the tongue and removing the 3 bolts that hold the hitch on. You might want to use a wire brush to to burnish the area. Just a thought....
2016 Siverback 33IK, Towed 40K+ miles
2018 Ford F-350 Lariat 6.7L V8 Diesel 4WD Crew Cab
Andersen Ultimate Hitch
RadMini Stepthru eBikes
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