Hitachi leaf blower RB24EAP

[hrz]

Have had this blower for about 6 years and it starts and runs beautifully in all kinds of weather until today when it started to sputter and finally stumbled to a stop. Cleaned the sparkplug (it was fouled) and cleaned the fuel filter in the tank. It started again right off but it sounds like the engine has a knock in it. What could be causing that sound?
Perplexed

 

[OldDiyer]

Just a guess but maybe broke a little carbon loose when you pulled the plug, maybe pull plug again and with it out pull the rope a few times to clear the cylinder a bit. Put the plug back in and see if the noise is gone. Just a wild guess had this happen a few times with car engines.