Remove guide. spring and piston. Piston washer is leather and held on by a countersunk screw on a dished washer. The pistons on these can wear where the cocking arm pushes as the metal is quite thin. If you know someone handy they could probably mig weld where its worn and file it up. I have fitted a Diana 25 spring to one I did for my niece to give the gun an easier life and to make it easier for her to cock. Worth thinking about if you only plink. Every thing clean and lubed? Put piston, spring and guide back in cylinder. (sometimes you have to push edges of washer to ease it into front of cylinder where cocking arm slot finishes). Place piece of thick cardboard on a block of wood on floor and place breech jaws down. You should then be able to put pressure on and screw block into cylinder. The cardboard enables cylinder to turn so you can get a part turn with both hands! Replace small screw on side of the cylinder.Replace barrel and pivot and lock screws. Do same with cocking arm. Replace sear and pin then (as with mk 3 post above) replace trigger spring and push up and forward to line trigger and pin. Replace action in stock. Tighten the 3 screws and refit rearsight. WEBLEY HAWK MK 1 next