I sent an email to NMA earlier in the week but I presume it must have got lost in the ether, I didn't receive a reply so finally I gave them a ring. The relevant technical guy was busy at that moment but he was good enough to ring me back later and talk through the problem/solution.
There are 4 bolts which fix the die cast trunion mount to the underside of the table, there are also 2 steel plates either side of the trunion mount bolted to the frame. The reason the mounting cannot be adjusted is because these steel plates restrict any movement of the mount. However the only reason for these steel plates is to avoid damage to the saw during shipping, so once the saw is with the end user they can safely be removed. This allows for 3mm of movement of the trunion mount (as the mounting holes are oversized), that should be enough to pull it into line. In addition each table section is screwed to the frame separately and each section can be adjusted separately so if the mitre slots are not quite parallel that can be adjusted too
I will have a go at adjusting the saw tonight and let you know how I get on.
G