That happens even to professionals with those inlets (with the non-return valve inside). If you can get the snap-on hose connectors off, it is but the work of half an hour to drop the Carver 2 out of the van - outwards, although you will need to clean off all the old sealant and re-seal afterwards. With the Carver out it should not be too hard to get the old valve out - if necessary, careful work with a hand-drill and scriber must succeed, but do not overdo the drilling and make sure that it is straight and central.

I should have fitted the high pressure pump today and tested the water installation, but I have in stead rested after yesterday's imbibitions!