Problem w 92 K1500 4 wheel drive

[ckhd]

92 k1500 'burb 170k miles, just bought it.

Wouldn't go in to 4 wheel drive. T-case shifts fine, after a few seconds, the diagram on the floor would light up, but if I got in a tight spot, only the rear tire(s) would spin, and it sounded like when you use your drill to screw in a screw, but strip the head... Kind of a buzzing sound, but slower and with more mass. Normally driving a 68, 69, or 72 -all with manual hubs and gear t-cases, I thought it was the actuator. After all, everyone complains about the thermal actuator.

I replaced the actuator. It still does the exact same thing. What are the chances of the problem being in the transfer case?

I think it's a NP 241.