Sorting out a Williams Grand Prix and I noticed that the "Same Player Shoots Again" playfield insert lights up, but the backglass does not light up when an extra ball is earned. I read on a different thread that these lights are wired in parallel, which tells me that if one insert lights, the other should also light. My initial thoughts are to see if there was a break in continuity from the extra ball relay up to the backbox lights. Would this be a good start?
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I was going to try it the easiest way I know how, find the lug with the same colored wires on them (W-GRN) on the relay side and the socket side, and use the continuity function on my DMM...unless I need to think about it differently?

The sockets should be good because the LEDs (I know, I know ) that I put there flicker ever-so-slightly when a solenoid fires. But I can still easily do this to confirm. Or I can jumper off of a controlled lamp (because I'm really a SS guy and am afraid of blowing anything up)

It's not the mechanical action per se, it's the electrical pulses (?) that make the light flicker, like what you would see if you put LEDs in any old game. Not noticeable with the backglass on.

There was a broken wire that should have been attached at the relay. It wasnt easy to detect on visual, because it was still "attached" but it must have been only by a few strands as it wasnt showing continuity. I resoldered it back on and all is good. Thanks guys!