Sounds like as you say the link pipe is leaking, which usually means the O rings need to be replaced.
O ring size is 9.91mm OD x 1.78mm Cross Section (BS 803 V) and are the same as the FZS1000.
The plastic T piece between 2&3 has different size O rings, but not sure of their size
O ring size is 9.91mm OD x 1.78mm Cross Section (BS 803 V) and are the same as the FZS1000.
The plastic T piece between 2&3 has different size O rings, but not sure of their size