I would start by checking the valve clearances to make sure there isn't a valve problem. Also may want to check the flywheel key to make sure it hasn't sheared.
By "running on" after the ignition is off, is it a dieseling sound or running like normal with the key on (but it is in the off position)?
"K&T Parts House Lawn Mower Parts and Chain Saw & Trimmer Parts"
Click on fourth manual down & download at bottom left of screen, page 8 troubleshooting, follow steps.
Posting this in case you need parts listed in future. Searching for coil. Search : eReplacementParts.comHi mechanic mark,
Thank you,Its awsome info.I think its the coil,(smoking and hot),have you got one and can u post to Israel?
Thanks and sorry about delayed reply but,we got some troubles in paradise