Replace the rope with a nylon rope of the same calibre and length.
Use the correct rope type for your specific trimmer. You can find the information in your trimmer's operator's manual.
Remove the bolts and lift off the starter and separate the starter from the trimmer.
Pull out the old starter cord completely. Attach the new starter cord. Ensure that the knot is as small as possible and enters the cut-out on the starter pulley. Wind the cord 3 turns anti-clockwise around the starter pulley.
Turn the starter pulley anti-clockwise
4 revolutions. Check the spring tension. With the cord
completely pulled out the cord pulley, it should be able to be turned at least another half revolution.
Thread the starter cord through the handle and support washer (A). Turn the washer so that the bevelled edge faces inwards towards the starter handle. Tie a small knot in the starter cord and pull it into the handle.
Hold the starter in place and pull lightly the cord to make sure the starter engages in the pawl. Tighten the screws and check that the starter works.