Thanks! I think you might be on to something there.
I have pulled the pipe that runs from the three way valve to the condensate chamber and I can’t see anything obvious. The none return valve in the pipe is still working and I can see the blue insert in the end of the valve outlet still.
That said, if I only crack the main isolating valve open to limit the flow to the machine then the dry cycle works perfectly.
Come to think of it I can hear the water filling during the dry cycle which I never used to be able to when the machine was working properly.
I have ordered a new three-way valve and condensate pipe and will update once I have them fitted.