Hello. Yesterday I had the opportunity to open up the fairly new to me CH150 Elite. When I got a bit above 45mph, a cyclical, rhythmic vibration started happening. The faster I went, the faster the rhythm and tempo of the vibration went. I know I need to replace the engine hanger bushings, because they rattle, but any other ideas? I am sure it could use a new drive belt, but the one on there isn't splitting or cracking, just a bit dry. What say you, master scooter mechanics?