All the chainwhip will do is take the cogs off, and you'd need two of them anyway. To get in there, you need to take the cover off (the ring with 3(!) pin spanner holes in the picture on the right), the cover is right threaded, heads up. From there, you'll have a gazillion bearings fall out and bounce everywhere. I have no idea how many exactly, but chances are there's an even amount on either side. So, when you reassemble, if you count up to an odd number, you're missing at least one of them.
Do this over something like a cookie pan, and not at a desk in your house in a room with semi shag carpet like I once did.
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Shimano : Click :: Campy : Snap :: SRAM : Bang