No 4WD-1995 Blazer

I have a 1995 Blazer with the on the floor shifter for 4WD. My problem is when I put the arm in 4WH nothing happens- no noise- no lights. When I put it in neutral and shift to 4WL, I can hear the gears grinding but it still doesn't go into 4 WD ( also there is still no light). I have replaced the vaccum actuator under the battery and the vaccum switch on the transfer case. These have not solved my problem.

Is there a fuse that could be burned out? Would low grease in the transfer case keep it from shifting into 4WD or do you suppose it could be the vaccum lines? Any help or suggestions would be appreciated. Thanks.

Check the shifter linkage arms to transfer case.
Is the shifter linkage rods moving the arms.
Are the lever arms tight and moving the transfer case shift forks rods?