Thanks for the speedy advice guys,
Daid,
It's an official kit, delivered last week. Thanks for the suggestion for replacement part, but sadly McMaster won't deliver to Australia so I'm a bit out of luck there. Also, Cura is fantastic, so thanks for that.
Joergen,
I had a look and the tube is a uniform inner diameter and outer diameter throughout the whole length. The geared extruder end is a bit wider after the countersink but still only a few inches of filament will fit until the friction becomes too high to force more in. :x
Sinar,
Good to know I'm not alone in this problem. I sent support an email on the weekend, hopefully they come through with a replacement soon.
It's a shame because the rest of the build was great and the machine seems really well engineered. To get to the last step of loading filament to find out it doesn't work is a bit disheartening.
Anyway, here is hoping support straighten this out ASAP.
CT