Much appreciated! I was just about to share the files with you when I read Ghostscape’s reply.
Why does Max do this!? Thank you! I have unchecked ‘Gamma Correction’ and it seems to have removed the nasty seams
For anyone else with this problem, I am running Max 2013 and it is under:
Customize > Preferences > Gamma and LUT > Enable Gamma/LUT Correction
It looks as if unchecking Gamma Correction takes a lot of light from the scene, despite my lights being turned up to around 1. I am sure I can adjust these to light suitably though.
Thank you for everyone's help with this!