It doesn't appear that there is a legitimate reason for the landlord to keep the remainder of your deposit, so you should be able to get it back. That said, court isn't a walk in the park, even small claims court. It will take substantial time to learn how to proceed in court and you will have to pay for filing and service. It is best if you try to just convince the landlord to pay.
That said, if you lived in a building with 5 or more units the Illinois Security Return Act will apply. If the Act applies, your job will be much easier because you can hire a lawyer and the landlord will have to pay the attorney fees, costs and a penalty when you win. If the act doesn't apply, you are stuck with a breach of contract claim that does not have fee shifting.
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