This little problem arises fairly often if you use your cupholder or let kids eat and drink in your car. Here is a step by step guide to the fix.

1) The window switchpack is located between the seats and there is a small recess for a small thin-bladed slotted screwdriver to be inserted allowing one to pry up the switchpack: 

Use you forefinger to push and pull on this projection to cause the front of the harness to release while you pull on the harness.

3) Once the harness is off, the entire switchpack can be brought inside for cleaning. Delight the wife while you disassemble and clean more auto parts in "her" kitchen sink. 

4) Here are the tools you will need to finish the job: 

5) You must now disassemble the switchpack. Use the knives to separate the sections of the switchpack by sliding them under and over the tabs in the plastic housing, on one side: 

6) Then flip the entire unit over with the knives still inside and pry with a thin bladed screwdriver on the other side to pop those tabs free, and thus separating one portion of the pack: 

Here is the bottom-most section separated as per above: 

7) Now repeat this process until you have separated all the sections: 

8) Eleven little metal rocker switches will inevitably fall out of place, so do not do this over your lap. (Don't worry, they only fit in one way and it is self-evident how to refit them. If you are still worried about it, here are the key hints: 10 of the 11 are identical switches with only one having dual pivot points. You will immediately see where that one goes. Orienting the rockers must be done by arranging them so the contact point/projection meets the contact point/projection of the inset contact in the board): 

9) Spray all the metal parts liberally with electrical contact cleaner and brush vigorously with the toothbrush. Inspect the inset copper conductors for carbon tracks (especially where the rockers make contact with the board) and concentrate on cleaning any of these completely.

10) Remove the clear plastic light conductor array (it conducts light from the single bulb to the plastic switches so you can see them at night) and pry the sections apart if you have not yet done so. You want to expose the plastic switches and pivots to clean all that dried soda and milkshake out that is gunking everything up in there. I soak mine first in hot sudsy water before pulling it apart: 

11) Using the toothbrush and dishwashing detergent, scrub the inside of the plastic switches and their pivot points and dry well.

12) Now reassemble all the dried parts. The location of the light and its recess is your first guide to reassembly of the entire unit. Replace the rocker switches in their respective mounts (remember the orientation tips in step number 8 above) and set this part aside. Replace the green light cover and the clear plastic light conductors in the thin center plastic section of the "switchpack sandwich." They go in so as to make the thinnest profile or layer. If that does not help, the plastic switches are hollow in order to accomodate the clear plastic protrusions so that they will go up into the concavity, bringing their light with them. Now snap this thin layer up into the top-most half of the switchpack, so that the clear plastic ends are oriented to enter the hollow switches. Now bring this part over to the layer that has the rocker switches sitting precariously in it. You must carefully snap the top to this without dislodging the rockers. It is not difficult, just be firm and smooth. Now snap on the bottom piece by lining up the harness connector slots to the connector tabs. It is ready to reinstall in the car. If you were reasonably thorough, it will work like it is brand-spanking new, until . . . the next cup of java finds its way down in there.