If there is no spark, there seems to be no point in looking for other faults until you fix that one. Are you sure you had isolated the kill wire when you tested the ignition system? Faults with brushcutters and chainsaws are usually in the fuel system rather than the ignition system, except where there is a problem in the kill circuit (on/off switch wiring). Failure of the tinpot switches they often use is reasonably common.
You did test the ignition by trying to make a spark from the high tension wire to earth, not across the spark plug, didn't you? Spark plugs don't last long in 2 stroke engines, so you never consider you have an ignition fault unless you can't get a spark from the HT wire itself.
