I have never seen the little bush on the valve wear, It'd be a first in my experience. I'd pull the valve out and inspect it first, hopefully the bolts won't be too badly corroded and you'll get them out without resorting to drilling out broken bolts.
Once you get the valve apart clean everything to remove corrosion and dirt, the valve should rotate easily in the little side plate. If not keep cleaning until it does, apply anti seize compound to the valve shaft and assemble. With the valve bolted in place it should turn easily by finger pressure only, connect up the pulley and check the cable adjustment.
It sounds to me as though the valve may already be free if you can hear a rattle, it might just be a case of lubing everything to quiet down the rattle.
Jim.