One of the secondhand kegs I’ve bought is a firestone (thought they did tyres) and the gas post is leaking. The poppet is a ‘three legged’ set up and my searches suggest there should be a plastic spacer between this and the plastic dip tube which is missing on mine. Can the poppet be removed and repalced with a universal spring type? Or is there an alternative gas post which will fit the keg?