Hi, I am looking at buying a 5m humber approx 2001. The seller has been very honest and told me that one of the tubes needs topping up after a few days, it has been like this for two years and not got any worse or caused any issues on the water. How worried should I be about this? Should I walk away? I gues it could be a easy fix if its somewhere easy to get at. or does it need fixing? Could it be possible that the leak can not be got to without the tube been removed?