I have a 2006 TYM 273HST with 400 pretty easy hours on it. A couple days ago I was smoothing out a small high spot in my yard a with my box blade. When I went from forward to reverse it made a popping sound followed by a noise that sounds like a heavy rattling grinding sound from underneath. The noise changes somewhat with throttle. Everything works except the PTO and it wont move in 2WD or 4WD. Any ideas will be greatly appreciated. I can't find anyone locally that can look at it before 2-4 weeks