Customer called us out for a clogged kitchen sink. On inspection I found that the most likely cause was grease and cast iron. I recommended running a tub gun because there was galvanized steel piping and I did not trust the k-400 to not break it. Customer agreed. I removed the ptrap and ran the tub gun down the line clearing the blockage. I then assembled the ptrap and tested it for 15 minutes. There were no leaks in the crawlspace or under the sink. Customer is not interested in having a sewer supervisor out.