Getting GT-511C1R to work with Leonardo

Hi, I'm currently having problems in getting Leonardo to work with the Sparkfun GT-511C1R fingerprint sensor.

I'm using this Leonardo board: |500x500

Fingerprint Sensor link: https://www.sparkfun.com/products/13007

The sensor is fully working on my Arduino Uno board however does not work with Leonardo, can someone help point me in the right direction in terms of fixing the pre-existing sketch to function with Arduino Leonardo.

Current Sensor code: https://github.com/sparkfun/Fingerprint_Scanner-TTL

Thanks.

Any ideas?