I don't know if it's cold weather or what it is, but I've had several leaking Husvarna gas caps here lately. Just a very slight weeping type of thing, but it's annoying. I bought a supply of replacement o-rings. Sometimes replacing the o-ring works, sometimes not. One saw I tried a new o-ring, it didn't work. So I put a new cap on and that did work. Try as I might I can't see a thing wrong with the old cap.
Has anyone run into this? Is there a slightly bigger o-ring maybe?