Locate the armature bar positioned just above the front coil. These parts should not be touching; however, if the machine is not working, it is most likely because the bar is touching the front coil, preventing it from bouncing up and down.
Locate the contact screw above the armature bar and twist it counterclockwise. Loosening this screw will increase the space between the bar and the coil, thus allowing the latter to bounce up and down.
Apply pressure to the tattoo-machine foot switch, turning the machine on, and make sure the coils are able to bounce correctly before dipping the needles in ink and tattooing skin.