If it's just an "O" Ring you can just reuse it. They make a good static seal but when placed into a dynamic load they tend to were some. Lucky for you it's a static seal. Just pull it off. Wipe with a rag NO CLEANER. Re install. It should be fine. Or once you pull it out you can go to the auto parts place and match up the same size from there assortment kit. It should be close enough to seal it no problem. Thicker is better than smaller.