On the landing rollout, sometimes I hear a noise. Not quite grinding, not quite scraping... sounds like I'm dragging a chain behind the plane. It's intermittent. Control inputs or brakes do not seem to affect it, it just comes and goes. New Lang tailwheel. I repacked the bearing, the races were smooth, no signs of seizure or chattering. I never notice it when taxiing to depart, only at slow speeds when I'm wrapping up the landing or taxiing back. I'm out of ideas.