97 f150 4x4 front hubs wont engage on 1997 Ford F-150

shifts to 4 wheel drive but front hubs wont lock

Asked by for the 1997 Ford F-150
is this auto lock or turn to lock?
Good question as the auto locks give a lot of trouble.
1 more answer
Change the fluid in the front axel and then tackle the transfer case. Change out thoese fluid and keep you eyes open for medal shards . Then take it'll for a spin