Study "Assembly.skp".

Obtain the following parts:

1) "6VDC 45 RPM Pinky Finger Sized Gear Motor 1" Long x 15/32" x 3/8"" from either amazon.com or directly from http://sciplus.com/p/MICROMOTOR_47952. Other sources are available, I've not tested them though.

2) Coaxial Power Jack - Radio Shack part number 274-1583.

3) 1.5 Vdc Power Supply - Radio Shack part number 273-315.

I used the same emmett's heart parts that I used in Geared Heart, Motorized Edition. "Emmett's Parts.stl" contains these (while it slices fine with Makerware 2.3.3.42, other slicers may have problems). The geared heart must spin freely on the center. If does not, pick a heart piece and insert one of the pins into the hole in that piece, then spin the piece while holding the pin. If the piece doesn't spin freely, remove the pin, make sure the inside of the hole is clean (e.g. no stray filament strands, I found quite a few) and and if not, clean it out with a modeling knife. Next, if still does not spin freely, slightly enlarge the hole using a modeling knife. Repeat this process for all heart pieces. The heart pieces should spin on their respective pins as easily as shown in this video: https://www.youtube.com/watch?v=o8CkCe5A-1w. 

Print "Base.stl", "Gear Main.stl", "Gear Motor.stl", "Heart Center.stl" and "Top.stl". While printing "Top.stl", I paused the printer when the printer z position reached 4.2mm, then switched colors from black to red to match the red heart parts.

Print "Base.stl", "Gear Main.stl", "Gear Motor.stl", "Heart Center.stl" and "Top.stl". While printing "Top.stl", I paused the printer when the printer z position reached 4.2mm, then switched colors from black to red to match the red heart parts.

Solder two wires (about 3" each in length) between the motor "+" and "-" terminals and the coaxial power jack. Slide the motor into the motor mount in "Base.stl", running the wires out the slot in the side of the motor mount, then mount the coaxial power jack in the hole in the back of "Base.stl".

Press "Gear Motor.stl" onto the motor.

Mount emmett's heart parts on "Center.stl".

Slide the shaft on "Center.stl" through "Top.stl".

Press "Gear Main.stl" onto the shaft of "Center.stl".

Press the assembled top into the top of "Base.stl".

Set the recommended power supply output voltage to 1.5vdc, then plug it into the coaxial power jack.