The Red arrow at lower edge of the circuit is the 0V, Common/Gnd line.
You cannot run the circuit at more than 5V, that is the max voltage rating of the new motor.

EDIT:
You could use 4 * 1.5V batteries as the d/s states.

 

ok thanks E,

I am getting confused between other circuits I previously considered.
I think I will have to go down the route with the batteries.

Really appreciate the help on this.