Knock out small pin through breech block and remove barrel plunger and spring. You can clean, lube and replace these now and replace leather breech washer if required. I suggest you knock out,lube and replace the pin through the breech jaws that the plunger locks against. Remove trigger adjster screw and spring from behind trigger.Remove trigger pins and slide out sear and trigger spring. The actual trigger is a 2 piece trigger with a steel blade that springs onto it and held in place by two dimples. I wangled the lot out and in but if you can "spring" the dimples it would make reassembley easier. Put pressure on end cap and remove cylinder end pin. Release pressure and remove cap, mainspring/springs and slide out piston. It has ususal rivetted washer which you could change for material and fixing of your choice as mentioned in 522 strip above. Clean and lube. Replace piston,mainspring and endcap and cylinder end pin. I think the correct way to replace trigger is to slide sear in 1st then wangle the trigger blade and triggr spring and finally the actual trigger piece in from the front and locate it on the dimples. Refit barrel and shims,pivot screw and lock screw, cocking arm and pivot and then replace action in stock and tighten screws. Refit rearsight if removed and tighten that lockscrew on top once sight is in place.