EC121
Your right about that fuel tank stopper. I have several of the WM ARFS and they all seem to use the same style tank. Just the size varies. Anyway the metal disk on the back of the stopper will viberate loose after awhile. I replaced those with a plastic one and that took care of that. Next problem is the stopper shrinks/loosens up and leaks around the tubes. I finally gave up on these and just automaticaly replace them with Hayes tank now. I use the Dremal to get it in and also leaves a little room for some foam around the tank,,