As stated above if the steering clutch is stuck you should exhaust every Possibility of getting it free'ed up without tearing into the Cat. If you can get it broke loose it will be just as good and last just as long as if you tore it down and a lot less expensive.
Loose juice is good but my method will not work with the loose juice in there. First adjust the free play out completely, run the Cat back and forth while riding the brake to heat the drum with the clutch released as far as it will go. I have had success with this method but it may be somewhat controversial.
If the problem is a failed throwout bearing it will have to come apart. This involves breaking the track, removing seat and fenders and jacking the Cat up off the pivot shaft and removing the final drive. You don't have to pull the sprocket but there is a lot of heavy jacking and lifting involved and be prepared to spend a lot of money on parts