Ford Repair: 1994 Ford Explorer 4x4 trouble, ford explorer 4x4, automatic locking hubs

Question
I have 1994 Ford Explorer 4x4 (automatic locking hubs/with push button in cab) and am having problems with the 4 wheel drive.  for the last fews months the 4 wheel drive has been attempting to engage on it's own (not really completing engagement) or it will not completely disengage.  While turning (either direction) I hear clicking and popping and then I hear a kinda of whine/buzzing until I re-engage the 4x4.  I'm not sure what the problem could be.

Answer
Explorers of that vintage had many problems with the transfer case motors. I keep a spare for testing purposes.
Sometimes the auto hubs will stick too. If the 4X4 light is flashing there may be codes stored that you can retrieve to aid in diagnosis.