Mech bolts
Ok I can do it with my bare hands, being an engineer an having the grip of a python, but the best way is to remove the b spring tension adjuster then grip the outer flange with some decent pliers No not needle nosed wimpy ones, I use a quality 15 inch pipe wrench, but decent clean jawed broad mouthed will do and grip this flange, then twist with a push so the stop flange on the other side clicks in place. Now you must hold the allen bolt and flange in together, while sliding the criclip back in place. It's very easy when U know how, but takes a bit of practice and needs a bit of strength.