Had a strange thing happen and am wondering if anyone has any knowledge of what the problem might be. First the 4x4 would jump out and I would have to pull the lever up and it would engage again. Then as I was plowing I noticed that only the front wheels were driving and so I went to park the tractor and took it out of 4x4 and then it would not drive at all forward or reverse. It also would not engage into 4x4 again. I'm hoping it is not an expensive repair. Does anyone know what might be going on?