Can you tell where its leaking from ? Nearside, offside, header rail ? Any damage to rubber seals ? Or areas you can see where seals aren't flat. Try putting silicone grease around seals with hood open and then close hood. Then open hood and see if any areas where the grease hasn't squashed on the other surface.
Has anyone heard about leaks through the actual fabric ? I think this is very unlikely though.....
Best of luck and let us know how it gets resolved.
DWH