This has been happening for some time.
However due to bearings and seals failure I fitted a new pump.
And thought that the intermitent fault would be fixed also. The old pump impeler blades were in good condition.
BUT NO !! failure to pump out is back …. intermitantly.
It can be made to pump by rotating the prog’ switch. My wife has the nack 😳
Any ideas would be appreciated
Regards flounder