Open Question: Sell private mortgage note?

I hold a private mortgage note for $100,000 on a $600,000 home. The note came due in 2008 but the buyer could not come up with the money. The buyer made all of the payments but stopped when the note came due. I have waited over a year for the buyer to refinance the loan but they have failed to do so. Can I sell the note or refinance it somehow? It is a 2nd mortgage, a bank hold the first.