If parts of the grout are missing around the problem area, you should vacuum any debris up and continue to drill and fill so that the adhesive seeps into the grout lines and helps bind failing/missing grout again. Then re-grout the entire area.If the grout is completely gone, or if it’s a newly laid floor, we recommend first trying to inject the adhesive before grouting so it doesn’t block the cavities, and then afterwards proceed with grouting. The grout will adhere to any adhesive that may be visible in the grout lines, so you don’t need to scrape dried Adin out of the lines. Make sure to clean the tiles with a damp sponge. If any dried residue remains, scrub it off with a white scouring sponge or use our Adin Residue Remover.