Tattoo Machine Troubleshooting 
#A133 Machine does not run.

Check Maybe The Contact Screw is not touching the Front Spring.
Good. The Contact Screw is touching  the Front Spring.

Contact Screw Troubleshooting Answer # A133
Problem	Machine does not run.
Because	Contact Screw is not touching the front spring.
Check	The contact screw must be touching the front spring.
Why	Electricity will not flow unless a circuit is complete.
Cause	The Contact Screw is turned too far up and is not touching the front spring.
Remedy	Turn the Contact Screw down until it touches the front spring (or the contact point on the front spring).

Also see  needle insertion in tube.

(Bring up separate labeled parts window) then re-size the new window and drag it to the side so that you can see both windows..