Just like to add that the critical setting of end cap shims mentioned is easily verified after assembly.
In truth we always check before dismantling 'cos may have been set up incorrect previously.
When correctly set the rack & pinion teeth will have back lash with gun not cocked.
In this state the threaded trunnions can be turned with finger grip after initial slackening.
If the teeth are under load the shim state can be checked by turning the end cap in increments.
If unscrewing produces backlash the shim is too thick. If tightening does it the shim is too thin.
Handy if no accurate measuring device to hand.