Yeah...I've done probably 4 threadserts on Toyotas for the same problem. The plug would unscrew(or strip out) and the Coil on Plug would hold it in place and the plug would bounce around and completely demolish the threads on the compression stroke. Ofcourse, every person opted for the cheap fix and to tap/rethread the plug hole with the head still ON. Lol....yeah...no warranty!