Drainage Channels

[jeffluent]

The black plastic drain channel under the screen has a hole in the centre.Rain water runs down this and emerges at the wing joints and from there,at least on my car,runs down the wing channel and runs out over the headlight.Is this correct or is something blocked somewhere?

[Luditus]

I hope your post gets some knowledgeable replies, because I would also like to know how the rain is supposed to escape.