Small Engines (Lawn Mowers, etc.): Idiot and his Tecumseh HSSK50, simplicity snow blower, winter storage

Question
Hi, I made a mistake and inserted the wrong spark plug in my Simplicity snow blower after winter storage, which uses a 5HP Tecumseh HSSK50 snow king engine. The plug was longer than the correct plug. When I pulled the cord, the tip of the plug broke off. I was able to retrieve the piece. After inserting the correct J8C plug, the engine won't start and it makes a knocking sound with each turnover when pulling the cord. I'm sure I damaged something. I'd like to try and fix it. I have some mechanical ability. Thanks in advance for your help.

Answer
Pat
Sounds like you did some damage on the piston and the rings. When the piston hit the spark plug  you may also bent the rod or cracked it.What you have to do is remove the head and check to see if you have any damage on the walls of the cylinder,or the piston crank the engine over and look for damage.