I never thought I'd be saying this, but I am so glad to hear that a hole that small can cause a leak. We have been dealing with a leak detection company, and he claims he couldn't find the hole, but he instead came out twice and did some repairs on the cavity of our light. That didn't do a thing. Now he thinks its the main drain and wants to plug it up to see if that helps any. I still think it's this hole. I need to just go down there and fix it myself. Thanks much for the link to your homemade patching system! I'm going to give it a try.