AC,
understand about powering the line when lowering the cargo door, but I think later marks of the C130 had a mod to allow power closing of the door.
Often after an airdrop the door would not lock down on one side. this was usually the RH side as you look aft. The loadmaster then had to walk up and stamp on the door thus effecting closure.
And yes we tried all manner of things in respect of removing kit from the door before airdrop sorties. It just seemed an odd design feature all round.