98 jimmy 4wd front wheels not engaging

Hello, I picked up a 98 jimmy for my son and turns out it has many issues! The one I'm tackling now is the 4wd. Front wheels don't engage "unless you can't tell on these on dry pavement just to test it,but,I don't feel it "crab walking" when turning. Things I've done so far ..... New transfer case vacuum switch, replaced any tore vac lines "I had Hvac issue which is corrected now that I've done this" replaced cable to actuator under battery. It's a 3 button switch and lights appropriately when selecting 4hi or 4lo.i can hear it engage and disengage and also hear the tccm click when I push the buttons.The cable pulls the actuator and the actuator moves and holds as it should which leads me to believe everything is working but why aren't the front wheels engaging?? Am I missing something?? Please help. Thanks in advance!!

If you are sure the mechanical portion of the engagement mechanism is working the problem would be internal in the axle.