Amazon.com still carries this model and has the manual available for anyone to download. The manual has detailed instructions on replacing the line. You can download it here.
http://www.amazon.com/Ryobi-700R-2-Cycle-String-Trimmer/dp/B000087QX2/ref=sr_11_1/002-5256994-2918455?ie=UTF8
Everett
April 2007