For the right ramp, the ball must make it completely around the ramp to count as a completed shot to turn off the white insert. I believe there is a switch on the right side after the ball starts coming back on the ramp/loop toward the right shooter lane. That is the switch that is likely the problem.
I would first put the game in switch test and roll a ball up the ramp and see if both the ramp/upward switch and the right/downward switch are both seeing the ball pass.
Let us know what that does after you try it so we can help figure it out from there.