I require item numbers for parts 7, 27, and 28.

It looks like you require the below. 0000 951 1114 - Screw M5 X 12 - https://www.lsengineers.co.uk/screw-m5x12-genuine-stihl-part-oem-no-0000-951-1114.html 4180 080 0401 - Cover - https://www.lsengineers.co.uk/cover-fs91r-genuine-stihl-part-no-4180-080-0401.html 0000 951 1114 - Screw M5 x 12