Thanks for the comments. We decided to go for it in the end. None of the other eggs were unzipped and only one visibly pipped so we felt there was not too much risk. We whipped out the hatched ones and sprayed in some warm water. I also picked up another tip which is to get a new, clean cloth wet, roll it up and pop that in. So far so good as 1 more has hatched and 4 more have pipped so I'm hoping it's all OK.
Another reason we decided to do this is that the chicks were rolling the other eggs around. I recall our best ever hatch was when we used cut up egg boxes to make holders at lockdown which stopped the hatched chicks moving the unhatched eggs. Needs a bit more space in the incy but I might do that next time. I have also read that 48 hours is fine. So maybe the best way is to fix them in place, pointy end down and leave them to get on with it?