The echlin MO3000 rotor tang....loose?

MO-3000 is old info, number one. Read this thread—it's long but worthwhile.

Number two, the loose tang you're seeing is an old problem—like at least two decades old. Pry the rivet out the rest of the way, put a drop of Loctite, reinstall the rivet and clamp it firmly into place with a bench vise or (carefully) a pair of pliers. Give it an hour to set up.