I had that problem a while ago, i asked my plumbers merchant (PTS) and they managed to locate a few spares that could fit, but take a picture of spares required or take in a spare to show them, but not all branches are as helpful as Maidstone.
Has anyone any idea how to cure a leak on a chrome flush pipe, from a low level cistern, tried plenty of PTFE tape, and new rubber washer, tightened up, but still leaks, this problem always occurs on chrome pipe, and not UPVC pipe.