Bosch flue missing black end terminal

[boilerhelpdude1]

Hi I live in an apartment which is on level 4 in my building so access externally would need a cherry picker. I notice the black end terminal is missing from my external flue (boiler is a Worcester Bosch combi). Is it possible to replace the black end terminal only ? Or does this need a complete flue ? It feeds externally through a bedroom wall to the boiler in the hallway cupboard so hoping to get this fixed without internal work .(There is an access panel to the first connection joint in the ceiling in the bedroom about 100cm from the external wall) Thanks

photos of my flue and also neighbours complete flues :-