I've tried sharpening, re-sharpening, and flattening the cap iron mating surface, but I can't get the plane to take nice smooth continuous shavings. It slices nicely into the wood, but the shavings are bunching up into accordion-like structures and getting clogged in the mouth. Anyone have experience with these planes? I'm not sure how to diagnose the problem, maybe the mouth is too narrow and need filing open?