
Apparently the fuel filter is a felt device. Inspected mine to see it was clean as a whistle. Never been a chance for dirty fuel or stale fuel. A wise old guy I know filters all his power machines fuel through a paper dust mask as it goes in.
I only ever used ethanol free 95, Stihl synthetic? two stroke oil at 50:1 mxed in a clear bottle so could see any crap if there was any to see.
The only thing I suspect is when the trouble started, the idle speed increased noticeably, enough to spin the string line assy. According to instruction I reduced revs to suit - string line unit not spin at idle. Returning th speed screw fixed nothin'