Tattoo Machine Troubleshooting 
#A137 Armature bar sticks to coils.

Short Circuit Troubleshooting Answer # A137
Problem	Armature bar sticks to coil when the  foot pedal is pressed.
Because	The electrical circuit is shorted out. Missing or not insulating washer.
Check	The plastic recessed washers insulate the front stand-off from the frame. If a metal washer is used or the washer is missing the machine will short.
Why	Electricity will flow through any path  that is created.
Cause	If the front stand-off touches the frame a  new path for electricity is created.
Remedy	Install plastic or fiber recessed washer which will insulate front stand-off.

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..