If the spark plug is stripped, replace it, if the hole in the cylinder head is stripped, the first thing to do is run a tap or thread chaser through the hole, if that does not work, you will need a helicoil http://en.wikipedia.org/wiki/Helicoil
yes but is is cost effective? that's your call
How easy is it to replace a spark plug wire on a gas weed eater?
Repair kit availale at most auto parts stores
To perform a weed eater spark plug replacement, first ensure the engine is cool. Locate the spark plug on the engine and use a spark plug wrench to remove it. Check the gap on the new spark plug and adjust if necessary. Install the new spark plug by hand, then tighten it with the wrench. Finally, reconnect the spark plug wire and test the weed eater to ensure it is running smoothly.
Your weed eater spark plug may not be firing due to issues such as a dirty or faulty spark plug, a disconnected or damaged spark plug wire, or a problem with the ignition system. It is important to check and replace the spark plug if needed, ensure the spark plug wire is connected properly, and troubleshoot the ignition system to resolve the issue.
Could be that the threads are stripped on the plug or the head where the plug is screwed in. Or maybe it's the wrong plug..
The spark plug for a Stihl FS36 is a Bosch WSR6F gapped at .025
Don't know much about lawnmowers but I work on cars. So either ur threads in the head are stripped and/or ur exhaust system is clogged, making the pressure come out of the weakest area which in your case is the spark plug hole
.025
.025
gap is .025