that sandwitch plate is weird... anyone else have a 1G with a sandwitch plate on the sump?
anyways im not sure how to explain how much silicon to use, i suppose use more that what u did before, what i did was run the stuff along the middle of the block skirt then when i got to a bolt hole i made a circle around it so the hole wouldnt get gunked up with silicone.
try to get the sump on in one go so the silicone only has to bubble/shape once, putting the sump on and then taking it off compromises the sealing shape by having already pushed alot of the silicone out to the sides and can cause leaks again.