Stripped out plug socket on head???

OK, this is a non-Fbody problem, but hopefully I can get some help here.

My little sister's 2.2L Corsica had some plugs installed by Ken Towery Firestone in December. At the time, it was missing and I replaced the plugs, ignition module and a bad coil, and was still missing. So I took it up the street to Firestone which said one of the new plugs were bad, so they replaced it, then it ran fine. Tonight after getting gas, she pulls out of the station and the car starts acting up, so she goes home. I open the hood to find the #3 plug and wire laying on the other side of the engine bay. The threads on the head for the plug are stripped out, none of the other plugs will screw in there and the plug that came out screws in fine in one of the other cylinders. BTW it has an aluminum head.

My question is what would cause this? Overtightening of the spark plug? Does she need an entire new head now, or can it be repaired? Should the Firestone have to cover this, since they are the last ones to mess with the plugs on the car, even though it was in December?

Need suggesions!

You may be able to have the head repaired, but I doubt it. It will most likely require a new head. I don't think Firestone is in error since the car has run fine for 6 months. You may want to check into recalls for this kind of thing and see if it is common. It may be a design flaw or something. :)

Here is what happens....

If the spark plug loosens up for some reason, it will begin to work its way out. Slowly, over time it will get looser and looser. Eventually it will only be held in by a thread or two, and the compression rom the motor will force it out, damaging those last couple threads.

Depending on how many threads are destroyed, you may be able to remove the head and run a tap through it from the inside out to clean it up well enough to get a plug in it. If the threads are damaged to far, you will have to put a heli-coil in it and create new threads.

Good luck.

Anyone have an estimate or suggestions on retapping the threads on the head with a helicoil?