Note that you will also need the No. 55 - Circlip pliers to replace this assembly.
We recommend that you send the machine to us for replacement of the motor assembly. If you still want to do it yourself you must refer to the manual. http://www.inkmachines.com/sites/default/files/Manual_dragonfly_eng-1.pdf
There are a few things that are very important. The motor must be positioned so that the connecting rod aligns with the groove in the piston, the Contactscrew motor negative must not be tightened to hard and the Rca contact must be installed and adjusted after the motor is in its correct place. With other words do not attempt if you are not good with mechanics.