Employer wants tuition money back?

I have a friend whom worked over 5 years for a private school. They went to school and the employer offered to help with tuition, but my friend had to sign a statement saying that they would repay the tuition paid by the employer if they did not stay one year after graduation. Now, a job offer came after graduation and the previous employer now wants my friend to set up a payment plan with them for the amount of tuition paid and they want to have this meeting before they give my friend their last paycheck. Now, I think that they have to pay thier employee the week pay they kept during employment 5 years ago. I also feel that since the general statement is not a contact for payment amounts, schedule of payments, and no specific details were worked out at the begining of the agreement that the agreement is not legally binding. So, the ex-employer is trying to get their money before the last check is issued to the ex-employee.

Can they hold payment of wages until an agreement is made for payment of the tuition? Is the orginal agreement legal? Can they make an ex-employee payback the money under a general signature under a statement?

This is occuring in NY State. Thank you.