hmmmm....
A few questions:
1) Did you change the plug the last time?
2) Did you use the SAME socket you are trying THIS time?
3) Are you using a "proper" spark-plug socket? (There is a rubber "bumper/insulator" ring in MOST proper spark plug sockets...)
4) Could the rubber bumper/insulator from a PREVIOUS socket be "stuck" in the spark plug hole... keeping you from "seating" on the plug?
Okay, so that's ONE thought... some more considerations...
You speak of "something melting off" on the plug... are the OTHER plugs coming out ok? (In otherwords, your socket works... just not on ONE particular plug...)
Are you able to SEE down into the hole? If it's on the rear bank of cylinders... can you use a little mechanics mirror (like a dental mirror, often "collapsable") and a flashlight (like a penlight or mini-maglight) and see down into the hole? Is there something down around the plug keeping the socket from seating down all the way over the hex-flats on the plug? (Please consider taking great care to REMOVE any obstruction if there is one BEFORE you actually remove a spark plug. It's always a good idea to "air blow" out the plug holes with compressed air BEFORE you remove plugs, so any little contaminants in the area between the plug and plug well don't "fall in" to the cylinder.... even little "sand/grit/metal shavings.... or even NUTS", (YES NUTS! CHIPMONKS munch on NUTS on the cylinder head of one of my cars cause it sits near an OAK tree... and I always make sure the hard SHELLS don't drop in there....).
hmmmmm..... something COULD be down in there... but I'd want to confirm that only ONE plug is having this issue.... if you can't get your socket over ANY plug, you have a different issue, such as an incorrect deep-socket for the tolerance of the plug hole diameter to plug hex-flats clearance requirements. Not all DEEP SOCKETS, even of the RIGHT metric across flats size (M17, M19, 5/8", 13/15", etc...) will fit on all plugs in certain applications. Sometimes you have to have a very "thin wall" between the socket I.D. flat and O.D. diameter...
Also, not all DEEP SOCKETS (if they aren't SPECIFICALLY plug sockets) have the clearance for the spark plug top to "clear" the I.D. and let the socket drop all the way down onto the hex flats....
Any of this help?
Keep us posted.....
-crisp
