4X4 stuck between 2 hi and 4 hi

I have a 95 blazer. Recently when switching from 4 hi to 2 hi it started making a whining noise in the passenger front wheel. When switching from 2 hi to 4 hi the whining noise stops, the indicator light on the floor turns on but the vehicle is definately not in 4 hi. I recently replaced the actuator under the battery and it checked out good. When I leave it in 2 hi and drive the whining eventually works itself out. Is that going to be a transfer case motor or can it be something more simple. Can a novice mechanic such as myself replace a transfer case motor by myself? Am I hurting the vehicle by driving it when it is whining?