The alignment tool showed that the LHS pair of tubes were in fact leaning towards the RHS pair and not in line with the blast as in the photo below (looking towards the rear).
|The white dot is the end of the alignment tool's threaded rod|
and slightly to the right (in the photo)
The inner mounting holes of the two LHS tubes were modified to be slots so that the LHS tubes could be jacked apart from the RHS tubes. In this way, the LHS tubes were made parallel to the RHS ones and held in place after tightening the fixings into the casting.
Once done, both RHS and LHS tube pairs could be seen to be parallel to the vertical cab front joining strap between the RHS and LHS tubes.
|Tubes all parallel to the strap between|
|The complete assembly in place (1)|
|The complete assembly in place (2)|
|View from the inside|
|View from the outside|
|It's come a long way!|