My Mantis tiller and Echo weed wacker both didn't want to run this year and replacing the spark plug and fresh fuel didn't help. I bought new carbs on Amazon for both for less than $15 each. The kits included new spark plugs, air filters, fuel filters, gaskets and the carburetor. Swapped them out and success! They've made the carbs very hard to clean by plugging the pins out to clean any gunk. But at the price of the carb kits, why bother?