What else can condo association do to collect from delinquent owners?

We have a four unit condo association in Chicago. We have one unit where we haven't received any association fees for 3+ years. About 2 years ago this unit entered foreclosure (and was basically abandoned). We've hired a lawyer to help us recoup our fees and protect our interests, but nothing is moving other than finding out just about every party has a lien on this owner's unit (IRS, County). Other than sitting and waiting, what else can we do?