My new to me AF-D f2.8 20-35mm, has a stiff aperture ring. It is a little annoying as when I overcome the friction to move it overshoots, by a stop.
I have the Japan screwdrivers and some of the correct grease, though I doubt it needs grease. Is dismantling the aperture ring on this lens difficult. I have stripped and rebuilt a 50mm AIS once before, but never touched an AF lens.