Assuming the forend cap screws, magazine cap screw, and magazine ring pin have been removed, the magazine tube should be free of any restraints. But of course that'd be too easy. The last thing you want to do is grab the tube and attempt to pull it clear, but if you can find or fashion a dowel that fits VERY snugly into the front of the mag tube - without expanding the tube, you may be able to grasp the outside with a padded pliers, then oh-so-gently see if you can twist the tube a few degrees to one side and then the other, and if it loosens you should be able to slide it out. I'd use this method as an absolute dead-last resort though, because the chance of collapsing the tube is staring you right in the face. You'd mentioned doing a complete tear-down of the '94. By that do you mean everything - as in lifter, bolt, lock and so forth? If so, you may be able to attack the tube from within by replacing the magazine cap and its retaining screw, then sliding a wooden dowel in from behind, through the receiver, and gently tapping to see if you can move the tube forward. My guess is that the pin groove on the top of the magazine tube is hanging up just enough on the magazine ring to make things difficult.