Print is never centered on the bed. What am I doing wrong?

Picked up a second hand 3D printer the other day. Build volume is 300x300x400. After much configuration and testing I have finally got it to print well. The only problem I have is every print is offset to the left hand side. I have correctly set the endstop settings in the config file and print bed size settings in Cura (which I am using to slice my models), but still cant get it in the middle.

I’ve attached a picture of my problem, as well as the settings I am using. Any help would be great!

Printer: CreatorBox 3d (Kickstarter edition) with Smoothieboard v1.0b and latest firmware.
I’m also running OctoPi 0.16.0 and using that to upload the G-code from Cura to print.

Slicer: Cura 4.3.0

Config file (using the latest firmware):