I dont think you can blame the tech if the spark plug already had a helicoil in it from a previous repair.I'd advise the head off ,which may be too far gone for another repair.This is costly re heads off with engine in situ.The oil to water plate cooler is a standard feature on many engines but I have yet to see one fail.Think you will have to bite the bullet on this one or DIY it....

V6 MTX
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