I have a 7900 that is about a month old. Once in a while it leaks gas. It looks like it comes from the cap. The o-ring has no knicks, I have tried snugging it and really tightening it. It will only do this once in a while. Does anyone else have this problem. I know this is a simple problem, but I have tried the things that make sense with no prevail. What do ya think.