So this can be simplified even more. You can remove the need for the springs by adding a stopped to the end of the rack gears and then putting them in a sleeve past the arm.
This means the gears would need to be longer (this could be an issue as I think about 280MMs will be the limit), and a very simple bearing could be used.
This means the gears would need to be longer (this could be an issue as I think about 280MMs will be the limit), and a very simple bearing could be used.