It's a motion seeking enforcement and/or to hold him in contempt. Whether it will be effective in a case involving only $900 is questionable.
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You can move to hold him in contempt and/or compel compliance.
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You would have to do an Order To Show Cause for contempt. The court will give him time to purge the contempt. Depending upon the order and what is owed, at some point you can do an income execution for arrears and the weekly or monthly amount of support.
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