[Herb Concord Ca]

Hi I can't entirely answer your question. Never had passages that were completely blocked. I can't see the internal passages but the water always comes out light brownish. If really dark, a judgement call, I repeat the cleaning a second time. Any surface you can touch feels really smooth and clean. I do mostly Tillotsons and Marvels. The sonic cleaning really takes off the surface dirt and crud. Help this helps.