Brocock Contour leaking filling fitting.

[MrChipShoulder]

There are two seals on the centre shaft, one large, one small.

The small one is definitely donut shaped and I suspect the larger one was once upon a time!

If both seals are donut shaped and I can simply measure them and buy new ones 'off the shelf' in those sizes, would they be of a certain rubber type?

The small o ring seems to be OK, the larger one is dead.

The large one is 2mm ID, 5.5mm OD, 2mm thick, black in colour and quite hard.

Edit,

Just had a hunt on rubbishbay and found a 2mm C/S x 2mm ID in Nitrile 70 Shore, £1.80 delivered in the UK.
I bought it and I'm guessing it will be OK. If not, it will just leak again I suppose?

Edit,

I just bought a BF fitting as well under their recommendation as a back up.