Ebay has a protection program, and even if the seller wants sales to be final, he has to give you a product that works. Contact the seller and then e-bay.

Try contacting Billy in the vintage machines section-he is a wonderful source of knowledge and may be able to help you for free :)

Thanks, I'll try to contact him and see if he has any ideas.

File a complaint with Paypal. I've had luck and not so good results with them.

Assuming you used a credit card for the payment, you can open a dispute with your credit card company. This is why I always use a credit card when paying by Paypal.

Sounds like your machine came with only one bobbin. If that's so, it may be the wrong bobbin. Also don't forget to insert the needle with the flat side to the left and to thread the needle from right to left. If the machine wasn't advertised as serviced, it may be in deperate need of oiling and greasing. Billy has wonderful tutorials for caring for vintage machines on this board, and is a tremendous source of information.
Maybe if you post a picture of the machine and what came with it, some of the other knowledgable vintage and FW owneres on the board will have some great ideas for you, too.
You might also want to check out the groups on Yahoo dedicated to Vintage Singers and I think there is one also especially for Featherweights.
Good luck! I bought one sight-unseen on the Canadian equivalent of Craigslist. I was very fortunate. So sorry for your bad experience!

If you have a manual check to see if the bobbin case is lined up right...I can't explain it here but if the needle plate has ever been taken off there are two grooves on it that must line up with the bobbin mechanizium. really hard to explain but I bought my FW on ebay and when it came it wouldn't sew and sure enough the bobbin case was flopping around. LOL Found this out on my 301 thru a good friend whose DH was a machine repair man. try it...it will not sew if its in wrong....sounds like it needs a really good oiling also...

This is just a guess, but it sounds like the tension mechanism isn't right. If the thread isn't being caught just right it won't sew. If you can't get it to work, and the seller won't give you any satisfaction, contact Ebay.
Was the machine advertised as in working condition, or as is?
For that much money, he should have to stand behind the sale and make it right! :|

FW takes a certain bobbin. It looks almost like the average meatl bobbin but it isn't the same at all. It is flatter and thinner. Also the featherweight sews better with the Singer needles. Singer needles are a teeny tiny bit longer from what I have read about them. Also the thread goes in the needle right to left. The flat of the needle goes to the left. There is a notch under the faceplate that the bobbin case has to be in perfect position to. Really there is not much that can't be fixed on a FW unless it's physically broken. Give the seller a very bad feedback and enjoy your machine, it can be fixed to sew perfectly.

judging from all the advice i've read so far i think it's much to soon to recommend complaints to ebay.

let's wait to see whether she gets the machine running after trying all the other steps recommended.