Ever since small engine manufacturers began building their engines out of aluminum, users have been plagued with one common and irritating problem: cross-threaded spark plugs. Unless one is extremely careful to screw the plug into the hole by hand for at least a couple of turns, the chances of getting it cross-threaded are pretty high. If this ends up happening to you, you basically have two choices:
1 – Take the engine to a shop and have it professionally repaired (which will cost you a significant amount of money).
2 – Visit an auto parts store and buy a “Thread Chaser” to match your particular spark plug and fix it yourself.