It all seems to be running well this morning, so maybe a thorough flush of water was all that was needed, as indeed the manual says!
Getting close to getting it dialled in and getting a reasonable 1:2 now in 28 seconds with 20g and its nice to drink. Not perfect, but after 300g of coffee through it, its the first one I want to drink.
However for all of them the puck appears wetter than I expected and has a few ml of water on top of it when I take the Portafilter out. it seems to steam off and the rest of the puck seems dry when I knock it out, ie it holds its shape in the knock box. Is this normal?