I'm doing a spark plug change on a 2005 Ford Explorer with a 4.6 V8. I got all of the plugs changed except for one. This one is apparently stripped. The plug is loose and you can easily turn it by hand, but it won't come out of the cylinder head and is stuck. I can keep turning and turning it but it never comes out. I tried starting the engine, hoping the compression of the cylinder would make it launch out with no luck. Any ideas on how to get it out?