good point, did not think you had to do that.

Only maintenance Stihl says to do on my trimmer is force grease into the head. It has a handy port that the tube screws right onto, a cheap zirk fitting kind of.

I found a Toro straight shaft weed wacker on the garbage pile-looked like new. The string head was missing. The lady who lived there said the head wouldn't stay on, and she lost it somewhere. I offered to fix it for her, but she said to take it.
I went to my favorite mower parts shop, and bought the whole new head. It is the kind that you don't have to take apart to feed new line into it. Just line up the marks, stuff the line thru about 5 feet, then cut it off opposite the end, and wind it in. Neat! And it cuts well, too.