My plug wires were WELDED to the spark plug. No amount of pulling was ever going to pull them off.. Fortunatly, the tips on the plugs would unscrew. So, I unscrewed them, with the tip still in the plug boot, removed the plug, put the plug in a vise, screwed it back on, and hammered it off with a piece of wood as a buffer.. Even in the vise.. They were still VERY difficult to remove..
I use anti-seize on the tips of mine now, and remove them occasionally, just to be sure I still can..
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