Inker apparatus includes an ink reservoir and a chamber communicating with the reservoir and in which chamber there is a piston movable against a spring bias. The chamber in which the piston is disposed is in turn connected to a needle through which ink is delivered. A solenoid is adjacent to the reservoir and chamber and is actuated in response to the finding of a defective die under test. The piston moves along with the reservoir and the chamber, and continues to move by inertia or kinetic energy after the reservoir and chamber have ceased their movement. The continued movement of the piston causes the displacement of ink from the chamber and from a hollow needle extending from the chamber and which in turn results in ink being placed on the defective die.
