Finding the leak is the easy bit! Getting resin into the problem area takes a bit of cunning. I resolved the issue by reversing the pressure used to locate the problem, ie. a vacum cleaner on low suction to create a vacum in the hull. Use a long artists paint brush loaded with epoxy resin and dab it on the leaking area. The suction will draw the resin into the gap where it can penetrate the timber and ensure a good seal. Slowly reduce the suction until a small amount of resin remains on the outside of the join. Problem solved.