On 03/03/2021 18:59, Rod Speed wrote:
Limescale in the valve getting in the way then moving when the
pressure builds?

Yeah, looks like it and the video doesn’t show any
evidence of significant waves in the water level in
the cistern as its filling. Or anything else physically
moving much.

Had a fumble around all the parts but didnt take anything apart.
Wiped the part where the water discharges in to the pan as best I could
and this appears to have solved the issue.