att he very top of the steering column is a lil drive in centering bushing / bearing. it can be repalced from the top of the column.. but is NOT the source of your binding.
more than likely, as awhtx said. the upper thrust bearing that lives atop the worm section of the steering shaft is bad.
you have to take the whell off, then dash top at a minimum.. then the vred.. the column and a small cast top piece come off the shaft..and the old bearing cage and rollers need to be fished out.. new bearing dropped in assuming worm shaft surface is not galled.. if it is.. polish it up best you can so a roller can walk onit. there is a race int he top of the cast piece.. they usually survive.. but are otherwise replceable.. once the thrust bearing is repalced.. get he cover on.. note tension.. don't want too much preload on the bearings or the lower one will give out :).. then again.. upper one may be chinese and may give out too!
lube box.. adjust backlash and test out.
spindle bushing wear will cause hard steering too.
post back for more info.. them boxes are EX to rebuild unless completely worn out