Methods of diagnostic test pattern generation for small delay defects are based on identification and activation of long paths passing through diagnosis suspects. A drive is provided for reproducing the recorded information from the information recording medium. The cross-sectional surface of the draw nozzle is periodically increased and decreased in time in its entire shape imparting region, with a value for the frequency of the oscillating cross-sectional surface being chosen less than 1 kHz, preferably less than 100 Hz. The electrocrushing drilling process is capable of excavating the hole out beyond the edges of the bit with or without the need of mechanical teeth.