When I was moving my dad's Jeep the other night, I was having trouble shifting in/out of 4 wheel drive. It would go into 4hi and then be difficult to get back to 2hi. I could not get into 4lo--the shifter would go past N but it never felt like it engaged 4lo--I think it was running 4hi at that time. His setup is 2002 sport with auto trans. Any thoughts?