The signs that Illinois is having one of its most frenzied primaries in years are everywhere. That includes political printing presses reporting the busiest time in decades and debate organizers having to limit participation because there are so many candidates. Fueled by a vacating U.S. Senate seat and a high number of House retirements, open contests in the reliably Democratic territory are offering a rare chance for the party to draw from a new crop of candidates. The scenario has left voters with mounds of homework ahead of the March 17 primary.