Yes that is exactly what my starter relay looks like. So if the ground is the mounting bolt that should be sufficient I hope. I still don't understand how this could happen when the car is hot but when the car cools down it functions fine?
it just may be coincidence that it starts cold, or it may be the relay. if it were me, i would get a new relay and make sure it is bare metal on metal contact to the body. my duster was a manual with a clutch safety switch and i installed a 727 .i wasnt worried about originality, so i just ran the ground off my relay directly to the body.