This ^^^^ is exactly what I was getting at. Obviously, you have some brains. Most times people ask for help and get a response, they argue. "Noit can't be that!". It's not about being right, it's about a process of elimination and you seem to understand. Your description sounds exactly like what mine was. It actually sounded like a bottom end knock, but of course it was not. It didn't do it all the time, but dang near it.
