MF, rip the bolt with the phillips head out - that is the grease port on the gearbox (most trimmers have them).
Probably ran too hard and too long without grease in the box and chipped a gear tooth.
It had some grease, sky blue in colour in there, but not exactly packed with the stuff. No contamination visible when I took a peek with a small LED light.
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I personally would be more inclined to ditch the trimmer head and buy a chainsaw end for it and make it into a pole chainsaw. How many teeth is the output shaft? or is it 4 edge flex cable?
9 teeth end about 7-8mm diameter.
