Mowerfreak, I would think that lack of use and leaving them with fuel in them is probably the cause of failure of 98% of them. The other 2% is from people not using 2 stroke fuel in them
Add to that, owners using 91 octane number fuel, or even worse, the E10 version, for their 2-stroke mix; then leaving them in the trimmer's tank!
These petrols have the shortest shelf life, at least of those on the Oz market. And then of course, there are the side issues with E10...
ATM my only operational two-stroke is a 1970s Echo CS601VL chain saw - and I commenced emptying it of fuel after every use, after leaded Standard petrol went off the market. Still runs just fine, on fresh 20:1 BP 95 Premium petrol/Castrol TT oil mix.
