Quick answer
Compare the conduct with the exact written terms and ask about enforcement in the issuing court.
Do now
Collect the order, due dates, requests for compliance, and proof of what happened. Separate payment disputes from transfer or parenting disputes. Ask whether a motion, clarification, or another remedy fits the problem.
Watch for
A missed payment is not automatically contempt. Do not suspend your own obligations as retaliation. Orders can require specific notices or proof before enforcement relief is granted.
Official sources
NJ Courts — FD modification application packet, NY Courts — Divorce frequently asked questions, DC Courts — Family Court Self-Help Center.