I have a Stihl FS 85 string trimmer which is old but is performing exceptionally well. My reason for reaching out is I would like to know if an option exists to have a blade edger option on this model ? I know some do but have not been able to determine if this model does. If it does have the option, might you help me to understand how to take the string trimmer head off and install the blade edger. Appreciate the help and guidance.