pilot jet o ring

hi all. Ive pulled the tk 26 carbies down yet again. Im having trouble sourcing the o rings that live at the end of the polyester plug that covers the pilot jet screw. Its about the size of a bees foreskin albeit a large bee ( maybe a march fly as theyre big bastards around here in march). I tried canberra bearing services after CMC with no luck. the o rings been obsolete for a while and the only ones i can source are on partzilla but im having a ethical and financial issue with paying a shitload of bucks for postage on 4 x 6mm od x 4mm idx 1.6 orings. The plug is necessary otherwise it wont idle,not that its idling well at the moment but that should change now that the jets are clean again. has anyone else had this issue. I was almost thinking of tapping it and using a screw to seal the pilot jet. 
