This is my first time doing metal work. I recently purchased a Hobart 210 MVP and have been using Youtube videos to learn how to weld. I filled in the hole where my in cab fuel tank came through the side of my 68 C10. After I sanded down my spot welds I noticed there are still some tiny pits. I don't see any light coming through the back side of the panel. Do I need to spot weld the little pits or is it ready for epoxy & skim coat? Any tips would be greatly appreciated. Thank You!