I show you what a ferrule is and how to remove a stuck ferrule (compression ring) with this tool. http://englishtoolco.com/ | See Jane Drill

⚠ Product Focus: Ferrule type crimp connectors have grown in popularity over the years particularly when fitting aftermarket electronics to vehicles. Particularly useful for fitting auxiliary power management systems, charge controller, etc. where “WAGO®” or screw type connectors are used. Wire ferrules, when used with the correct crimping tool, replace the need for “tinning” the wire ends with solder. The ferrules are crimped on to the end of a bare wire to improve support of the wire and the c