92 B2600i 4X4 not engaging

When I shift into 4 wheel, I can feel it shift in the transfer case. The light comes on stating 4x4, but the RFW light does not light up. I haven't switched into 4 wheel drive for almost 2 years, I had it parked until I could replace the drivers side axle shaft that connects to the differential along with the inner / outer CV joints. I see a small canister with an arm that engages the 4 whl drive, but it doesn't move when the vehicle is shifted into or out of 4x4. I've read somewhere I could disconnect that and manually lock it into 4 whl drive by moving that arm, but I prefer not to climb under the vehicle everytime I need it.

Any ideas?