jdinner

It sounds like your IWE are working correctly. It could be your electric shift motor at the back of the transfer case. You will need to jack up the front end, key on engine off, 4X4 on and see if the front driveshaft out of the transfer case will spin. If it does your transfer case is not engaging the front shaft. You should not be able to spin the front shaft while the rear wheels are on the ground, 4X4 is on and the key is on.

Solid_Crimson

With the front jacked up in 4x4. I spun the driver and passenger tires and get a clicking noise like the IWEs are not locking.

jdinner

After reading about all the IWE's filling with water I took mine out as a preventative measure. I clean them on the outside and tested their ability to stay in position by holding my finger on the vacuum port. They were not moving enough to work properly. I used 'Honey-Goo' in the vacuum ports to free them up and get them working properly.
They work properly now.
To remove them I only disconnected the upper ball joint. Remove the three small IEW bolts, remove the IWE with the axle from the hub, there is enough room when you turn the steering wheel.