Just press the cylindrical housing on the sides (where the string goes in) and then turn counterclockwise.
It should get detached from the main assembly...
Just keep on trying, 'took me a couple of tries to get it out.
Then just put it back reverse of the way you took it out.
Just make sure string is pulled with the right length when you put it back, so you don't have to adjust it later on.
N-trimmer, July 2009
