This may help you. Ignore the first part and jump to 4.00 minutes. From what I can see from your pictures you are halfway there. Usually, the next stage is to Unscrew the focusing helicoid backward. But be careful to feel when it will come away from the body and mark that location on both parts. Like servicing any lens, be sure to make marks on each helicoid part so when rebuilding you know where the helicoids screw together ... they are usually multi-threaded. When replacing final front ring, do not over tighten the ring, and do not over tighten the screws which keep the ring in place ... this can lead to a stiff focus. Strange, but true.