John
I can't see any dripping but there is an obvious wet patch on the floor where is has done. I have checked all round the pipes where i can see without ripping up the flooring and can't find anything leaking
The wet patch is the evidence of your problem I'm afraid...the leak could be deep inside the boiler or water could be running along pipes and dripping quite a distance from the actual leak. The chances are the boiler will only leak once you have repressurised it, of course.