1) Scrape the inner side of the F3 cap by a reamer with a vacuum cleaner.
2) Cover the cap onto the base plate of F3.
3) Hung the F3 and put it on the end plate inserting the maraging wire for BF.
4) Removed the cap of F3 to access the keystone.
5) Lifted up the BF to hook the maraging wire.
6) Released the keystone of F3.
