There are many different components of the ignition system on a chainsaw and any time these parts aren't working they will misfire in the chamber, which can make starting the chainsaw impossible. A weak spark on a Husqvarna chainsaw can be caused by one of these misfiring components in the ignition system. Properly maintaining and cleaning the saw on a regular basis will prevent most spark issues. Most problems can be isolated easily and fixed with a few simple tools and parts.
Use the screwdriver to take off the top cylinder cover, which houses the air filter and spark plug. Take off the air filter and clean it with a rag.
Use the screwdriver to wedge off the spark plug's black rubber plug. Be careful not to damage this wire or plug when removing it. Check this plug and wire for any damage or loose connections. Replace the plug or starting wire if necessary.
Fit the socket wrench over the spark plug and unscrew it from the engine.
Clean the spark plug with the gas, toothbrush and rag; make sure the tip isn't damaged or heavily corroded.
Check the spark plug's gap (refer to your model's user manual for specific spark plug gap measurements).
Fit the spark plug back into the rubber boot but don't attach them to the engine. Hold the spark plug a short distance from a metal spot on the engine block.
Pull on the starter cord and check for a spark across the metal and spark plug. If there's no spark, replace the spark plug and repeat the test. If there's a spark, the saw probably isn't starting for another reason.
Always wear the proper protective equipment when working with chainsaws.