04runner- You'll find out when you clay. If you have to get aggressive with it, (which you will if the contaminants are under the SG), then you'll have to reapply the SG. That's because you'll have to go through the SG to get to the contaminants. But I'd be surprised if you had to REMOVE it first as a separate step. With only two coats of SG, it's hard to say without seeing it.