Unfortunately there is no "earnable" extra ball on Tron Pro.
The only way to get an extra ball on Tron is from an arcade award, I.E. "Light Extra Ball" and "Extra Ball"
Tron owners (including myself) have been screaming at Stern for an earnable extra ball since the machine came out but it has fallen on deaf ears.
The arcade awards are completely random and hardly ever show up. The adjustments menu does nothing it is a big tease.
