Jim94F150

My 94 F150 (4x4) wouldn't go into 4WD mode when I pressed the button. I'd hear a click, the lights would dim slightly, and then soon after a quieter click. The lamp would not light.

I tapped the motor on the transfer case, and the transfer case, with a hammer. Now it works normally.

Question: should I check the fluid? And/or should I replace the control module (which I guess is part of the motor)?

Thanks!