Tips on Buying Cars: Buying a car and release paperwork, legal standpoint, co signer

Question
Not 100% sure if this is the right area that I need to be in, but I have a question about purchasing a truck.  I'm trading in a vehicle that was co-signed by my ex girlfriend.  She is refusing to sign off on the loan to clear all financial responsibility. I have records showing that I have made all payments on the vehicle. If she refuses to comply, is there any legal way that I can go to court to get compensation on what I have paid on the loan?
Also, how does her refusing to sign affect the outcome of my new purchase?

Answer
Did she merely co-sign the loan, or is her name on the title of the truck, as well?  If she's only on the loan as a co-signer, then there's nothing you need to do other than payoff the loan; once it's paid, her responsibility is done and you can do with the truck as you wish.  Now, if her name is on the title, then she would have to sign off before you can trade or sell the truck.  If that's the case, your next step is to contact a lawyer and see what recourse is available to you from a legal standpoint.  I'm not a lawyer, so that's as far as I can advise on this.  Good luck.