I have had the strimmer for 3 years and it has always started well however despite following the instructions carefully the cutting nylon line never feeds out. Once the exposed length has been used up the line inside the spool has either fused with itself or totally jammed so that it has to be cut away. I guess that the ground has to be prodded now and again (although there is no mention of this) to allow more nylon to feed out but no luck. Any ideas?