If you have no spark it is highly likely that the magneto coil assy is at fault which is one of the most common cause of gradual starting problems on small 2 stroke motors of all types. This will cost you between £35 and £40 to replace and so assuming the strimmer is a good few years old its probably not worth it
John Rogula
September 2012
Ignition module required.
pleasant
December 2008
Additional info: I have removed the spark plug, connected my test plug and held the test plug against the motor. When I pulled the cord the test plug wouldn't spark.
(The test plug has its thread cut away so that there is a 10mm gap between tip and body of the plug. In previous testing on many motors, a healthy spark has always been able to jump the 10mm gap.)