John Z.
How to replace the cutting line on a STIHL FS 70?
The procedure depends on the head type: for AutoCut, tap the head on the ground while the engine is running to release line; for TrimCut, stop the engine, pull and turn the spool housing 1/6 turn counter-clockwise, then pull the line manually; for DuroCut and PolyCut, stop the engine and insert pre-cut line segments directly into the head.