In removed heads to fix a gasket leak and saw the leak then.
also remove the radiator cowl cover (4 screws) and have a look at the top of the tank, you will see a screw each end, this is to hold the lower cowl piece on.
The plastic under the screw is very thin, many of us have had coolant leak from the screw hole as it seems to screw directly into the coolant tank.
usually fixed by putting some form of sealer putty in

