I have a 2004 Yamaha big bear 400 4x4 and im having a problem with it. I had the rear diff rebuilt about a year ago and i think it went out ago but im not sure. When it is on and in any gear it wont move. When it is turned off i tried to push it when it was in 1st gear and it i could tell it was in gear but was alot easier than it should been to push in first gear. What is the problem, is it the axle, drive shaft, or rear diff? It is also a straight axle if that helps.