Lets get rid of the direction switch altogether and replace it with a second pushbutton!
Would be easier to control: Push the up button to move the focuser in, down button to pull it out....
Wouldn't be hard, remove the current switch and the motor drive circuitry, add a second one-shot circuit and a H-bridge circuit for the motor drive. Hmmm.
There's a H-bridge circuit
Here but it would need some logic 'glue'.