What are some good methods of recovering key function after a spillage? So a friend just gave me his Macbook Air 1,1 on which he spilt some water. He wiped it away immediately, turned it off and upside down but alas the "l" key is no longer functional. However all the others are. 

PRAM reset, no luck. Lifted keycap off, nothing unusual visible but still doesn't work. I'm going to leave it off and evaporating for a little while to see if that changes anything, but any suggestions would be great.

Incidentally, he also is still covered under Applecare. Can we get away with a repair on this? There's no water damage marker is there?
Apple are very likely to repair this under Applecare with no charge. I have had several defective keyboards and stuck keys in the past. In all cases, Apple replaced the keyboards for free under Applecare. 

Clearly your milage will vary, since if you have damaged the keyboard by misuse they are under no obligation to fix it, but in my experience, Genius bar engineers will always give you the benefit of the doubt.