How do you clean drains? I know where they are but how do you clean them?

[saaber]

Had lots of water pool in the area underneath the back window. It looks like the drain on the drivers side under then top is the culprit. I tried sticking a wire down there but it only goes in a couple inches through the hole in the metal (not a couple inches form the top of the foam). Used this method for saab convertibles in the past (ran wire up from bottom) and it worked great but can't get it to work on the boxster.

Is this drain a very small plastic tube that runs down to the bottom of the car? What does the drain itself look like? (plastic tube, rubber cone, etc.) How have you guys cleaned it? found the diagrams and discussions here but they don't say how to do the actual cleaning. Thanks for any help.

Man that foam holds a lot of water!