If the circlip is to much out of center you can pull untill your head turn blue,
and the circlip then can become deformed and make it more difficult.
If you meet to much resistance, stop....move the joint a bit forth and back
along the pinion shaft, while holding the FD with the shaft pointing straight
up....also a few gentle knocks often helps.......all this to bring the circlip as
close to center as possible....it can be several attemps before succes.
A impact chock usually function better than brute force to bring the circlip to
center and expand it......I'm using a slide hammer whenever it's possible on
shafts which is secured like this.