My early '04 auto locking hubs were froze up. I could barely turn one with pliers. I had nothing to lose so I drilled a 1/8" hole in the edge of the hub to try to flush out anything that might make the selector knob freeze up and to get as much lubricant in that area as possible.
In this pic you can see where the hole was drilled.
There is a rubber diaphram that you must not drill into or in front of, otherwise the hubs won't hold vacuum. I just measured inside the hub down to the diaphram, and referenced that to the outside of the hub,landing the hole behind the diaphram and in front of the selector knob. The measurement from the edge of the hub was 1/2".
Initially I used pb blaster to get all the grime out. Then I flooded the hole wth silicon lubricant, and worked the selector knob back and forth.
I chose a lubricant that was not harmful to rubber. I also cleaned the inside and regreased the locking hubs. It took quite a few cycles before it freed up enough to be able to move by hand. One was working much better than the other. I reinstalled the hubs, and drove it for a while, after trying to move them again later, to my surprise they both are working better since I reinstalled them. There will be excessive fluid that will drain from the filters and holes for a few days. You can then put a dab of silicon over the hole to plug it back up, after you clean them up. I hope it works for you.
Sent from my phone that somebody didn't help me get.