[Dave Flowerday]

It sounds like the ultimate goal of this code is to allow the operator to move the arm up or down as (s)he pleases, while restricting it from traveling too far. If these are the only requirements, then does the software really need to know which way it's going? It doesn't seem like it to me. Why not just set the PWM output to either move up or down based off the OI control, unless either light sensor sees the white paint - then clamp the PWM to 127.