i have the 128 ld model, so your trimmer head may be different
on the head, exactly 180 degrees opposite one another, are two indented black "buttons", both shaped somewhat like elongated D's, with one curved edge and one straight edge
press in on these and the internal tabs should release, allowing you to pull the head off
yes, so much is stated in the manual
just how does one determine when the bevel gear is 3/4 full?