How to clean a North Face Nuptse Jacket???

I have a North Face Nupste Jacket which I have been wearing for 2 winter seasons now and is looking very grubby - especially around the sleeves.
Can anyone tell me the best way to clean this jacket? Is it something I can do myself? or do I have to take to a Dry Cleaner???
Thanks for any help you can offer. I daren`t stick it in the washing machine as I am not sure what will happen!

Really, but make sure it is a product designed for down, (pure soap) As always keep washing down clothing and sleepign bags to a minimum becasue washing them will have a negative effect on the down. Make sure you thoroughly rinse the jacket after washing it. Soap residue will effect the loft of the down.
Lay flat and squeegy out as much water as possible or run it through the spin cycle of the machine several times. Let the jacket lay flat in a warm place and turn the jacket over regularly. When almost dry place jacket in a cool dryer with a tennis ball or two. The tennis balls help break-up any clumps and help the down regain its loft.

The North Face`s website says the following:
How do I wash my down jacket or sleeping bag? Periodic cleaning of down sleeping bags and jackets is essential to maintaining maximum loft and ensuring the long life of the product. Though it is possible to wash your own down product, we recommend that you have your jacket or sleeping bag professionally cleaned by a service that specializes in cleaning down. If you do not have a cleaning service in your local area, you may send your product to the Warranty Department, and request that we send it to our cleaning service.
Western mountaineering gives the following instructions for cleaning down: http://www.westernmountaineering.com/productcare.htm

For my down bag the instructions were: wash in a commercial front loader (I used Nikwax Down Wash), dry low/delicate w/ a couple of tennis balls until the clumps are gone. Took quite awhile to dry.

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