The blue light at the bottom of this table

[EccentricFlower]

"Releases Power Orb when lit"

But it's always on, and doesn't seem to actually indicate anything about gameplay at all.

Is this a TPA bug or was it a useless light on the real table too?

 

[Fungi]

At the start of every ball, there is one ball that lies awaiting for you to release it. The blue light indicates that it is still available and waiting. To release it, you light up all four light in the inlanes and outlanes. Once that ball is released, the blue light unlights and remains unlit until you start the next ball.

 

[EccentricFlower]

Ah! The guardians. Right. The instructions discussed that feature but didn't mention that light, only the four indicators in the lanes.

(I have never once actually completed all four of them so of course I have never seen the light go off!)

 

[Fungi]

Sometimes it works as a lucky break if you happen to complete the 4th light as you lose your ball thru the outlane.