Mine are extremely hard to turn as well. Had to build a special tool to have with me in the case I need it. Haven't needed it yet because my whole vacuum system is in good shape. Since I have owned it, I have serviced the Autolocking hups twice: Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page
I know that the problem with the knobs turning hard is very hard to fix. I guess there is an o-ring just inside the case that swells over time from petroleum products (what I read somewhere) and makes it hard to turn. You may be able to lube it with some spray if it isn't too bad yet and make it better. Many people purchase the after market Warn hubs. The downside is that these are manual locking hubs - not needing the vacuum system. IF you want new Auto-hubs from ford, I think they can cost about $200 each if I am not mistaken.
I know that the problem with the knobs turning hard is very hard to fix. I guess there is an o-ring just inside the case that swells over time from petroleum products (what I read somewhere) and makes it hard to turn. You may be able to lube it with some spray if it isn't too bad yet and make it better. Many people purchase the after market Warn hubs. The downside is that these are manual locking hubs - not needing the vacuum system. IF you want new Auto-hubs from ford, I think they can cost about $200 each if I am not mistaken.