Many thanks Tom and Roger. We'll make a plan ...
We bent one of the tubular axle fittings and bought a replacement from CT. The new part was very badly fabricated. They'd reinforced it by welding on a reinforcing plate - so it's obviously a known weakness. Problems were that they hadn't reamed the tube subsequent to welding which meant it was heat distorted. The action of installing it also meant the powder coating completely flaked off the unit. Very bad engineering - if we hadn't been on the other side of the globe we would have returned it.
The the bolt hole was not placed accurately which meant alignment was way out and impossible to adjust without distorting the hole. The remedy is apparently to weld a washer over the enlarged hole in the correct location. I know this is possible, but we're talking microns of adjustment required to bring the alignment back to spec ... and even if we manage that, we have the same problem of a heat-distorted tube.
One question I have, which I couldn't find in the Matco manual, was about the mechanism for adjusting camber and alignment. Is that part of a new axle assembly, and if so, does it come as part of the wheel assembly?
Bottom line - and thanks for the info - is it's clear the best solution is to replace this part with a Matco system.