I've read a couple different threads, the 4x4 seems to engauge and disengauge as i drive with it in 4x4 hi or low. i lifted the truck and check the tire rotation when off in 4x4 when the left tire moves forward the right tire goes backwards. the front drive shaft does not completely rotate but it does roughly a eighth or quarter turn, I'm not sure what to do next please help. thanks!!!