Seller issues after we've signed and I've found a buyer.

[Kevin Henderson Jr]

Quick issue. 

I have a seller that's basically wanting to back out of our Purchase and Sale agreement. Here's the deal. 

Home under contract for 25k. I have a great offer and I was preparing to pull the trigger and execute the assignment. 

The original seller is now attempting to back out of our deal and not sale because he's not going to receive the entire amount as he owes roughly 1k in back taxes. 

Our contract with the agreed upon price and clearly states that he MUST pay any owed liens/taxes when the home is sold. I spoke to him about this before either of us signed. He was ok with it and signed. 

My question is, should I go ahead and sell the home as we originally agreed? Will I face any legal issues since I can't physically make the guy take a check?

Will their be any potential trouble if I go ahead and sell the home without the original owners cooperation?