I have a 2011 sportsman 800. The 4wd isnt kicking in for some reason, when i flip the switch the dash says its in 4wd though. The shaft from the motor is turning, and the smaller shaft going from the main shaft and into the diff seems to be turning as well. Both CV axle shafts appear to be turning into the diff as well. I changed the oil but nothing improved. Any ideas as to what to try next? I'm wondering if there would be anything wrong on the inside of the diff?