I have a 2006 2500 6 speed. Since the truck was new the 4-low doesn't engage but 4-high works just fine. It is an electronic t-case, I can hear the 4-low trying to engage but it never goes in. I do not wish to take it to the dealer as usual. Anyone else had this problem? Do you think it may need a new actuator? Or could it be in the T-case?