A while back I put a 15 tooth sprocket on my kfx 400. Today I went to change it back to the stock 14 tooth and when I was loosening the four bolts to loosen the chain, two of them locked up. I got the other two tight and the other two were locked up. I tried loosening the other two again and then they locked up. So now all of my bolts are locked up and I can't reallly drive it and I've tried kicking on the wheels and can't get anything to move. I was going to take the rear sprocket or the guard on the bottom off to see if I could get to the bolts but it looks like the bolts go in to some kind of enclosure. I've been riding through a lot of mud and water but I don't know if that has anything to do with it.... Anybody know what could be wrong?