Thanks, everyone, for your helpful tips! I bought a couple of seals from Lowe's ($1.98 each -- too bad I didn't call Mansfield, but they were cheap enough). The guy at the store thought I needed to unscrew the piece near the bottom of it. The tube going to the flush valve is dirty and looked inflexible, so I didn't even try just pulling it off. After a couple of unsuccessful attemps, I went to the web and found these postings. Watching the video was the most helpful. http://www.griggindustries.com/product130.html Now I understand why everyone was saying it was easy. It took me about two minutes once I knew what I was doing.