[James_bf]

Thanks Russell and GTLEGEND,

The part GTLEGEND links to is the correct part.
Unfortunately the local Repco didn't have one and Melbourne is in Lockdown.
Was leaking too much to leave it for a while.

So, need a screwdriver to lever it out as it is surrounded by a plastic tube, the barbs hold it in otherwise.
I had a general plumbing repair washer kit from Burnings and one on the rubber washers was almost the correct size. Pull off old washer, press in new one and trim slightly around the edges.
Fits Ok and seems to stop the leak - fingers crossed.

Thanks,
James.