Mike, you need to unscrew the the black collar around the tumbler in order to remove it. With the tool correctly installed, it simply unscrews ( although you may need to use pliers to get it loose ). After re-installing the new one, just tighten the collar as far as it will go by hand, remove the tool, and turn the collar counter-clockwise until it locks. Don't waste your time trying to clean anything in an attempt to fix it. Anyone who has ever had to replace a tumbler without being able to insert the key and turning it, would agree that it's not much fun. Good luck