Mark,
I have today been making a cardboard model of fine horizontal adjuster, based on the principle of the Barn Door tracker also known as a Haig or Scotch mount.
Here is a top view. It will need a spring to hold the moving platform against the adjusting screw.
Here is a view from the side:
I have not yet worked out how to make the vertical i.e. tilt adjustment. The Bosch GLM250 weight is 0.24kg.
I wonder if the Riegel engineers can come up with some ideas that can be implemented without an engineering workshop.