Couple of years ago, I purchased a WoodRiver #4 from WC and it worked so great that about a month later, I purchased another #4 in a 3 plane set. Cut to now...I broke out the unused #4, cleaned it up, sharpened the iron and for the life of me, I couldn't get it to give a nice, fine consistent shaving. I even tried switching iron/cap iron assemblies, but that didn't work either. I finally called TS at WC and after a few steps, he said it could be the frog casting and I could take it back to the store to get taken care of. Now I did notice that it had the old style, angled yoke tip, rather than WR's newer rounded style yoke tip.
Anyhow, took it back, got a new one, cleaned and sharpened the iron and voila...nice, clean, thin consistent shavings. So, was it the sole, the frog, a loose nut behind wheel or what? Gotta say, these are nice planes.