I have a vintage Hammerli Co2 single shot air pistol tap loading. it takes the short soda stream air capsules, that seem to last forever. Great little gun but is in need of servicing as it leaks air when fitting a new capsule, so i assume its a O ring renewal throughout the gun. Any tips to do this or a kit of O rings. Would there be a recommendation of servicing in the instructions which i don't have. Any help would be appreciated.