I just recently picked up a used (in nearly new-condition) FS80R and would like to replace the flex cable shaft with a solid drive shaft, which is found in the FS85R (see exploded diagram below). For those familiar with this modification, may you please provide some insight on the specific parts required and the installation procedure. Thank you in advance. (1) Is the process as simple as removing the gear head assembly and simply pulling the cable shaft out and inserting the solid shaft? What about lubrication; does the trimmer tube need to be re-lubricated prior to installation and, if so, what type grease is recommended? (2) Do I need to replace the "flexible liner" (#8) along with the "solid drive shaft" (#7)?