Although every state is slightly different, if you have any felony convictions then you are likely disqualified. There are also certain misdemeanors that will disqualify you in some states, but those are somewhat rare.
If you received a deferred sentence while you finish probation or parole and have since completed probation or parole, then you will likely not be disqualified. However, if you are currently on probation, then in most states you will be disqualified from service until after probation is complete.
Call the court and explain the situation. You may be excused without having to come in at all. Your situation sounds like one that, in most states, may allow you to be disqualified by a clerk over the phone and not have to see the judge.