Found out something interesting... when I turn the impulse engines on using the pushbutton switch the light in the saucer dome over the bridge flickers and goes out. When I turn the impulse engines off the dome light comes back on. I surmise that there is only enough amperage available for the two N ports on the saucer PC board to power 2 LEDs as the N ports were intended to only power 1 impulse engine LED each per port. So I have 2 LEDs for the impulse engines running off one N port and 1 for the dome light running off the other N port for a total of 3 LEDs on the N ports. So I have to choose having the impulse engines off with the dome lit or the impulse engines on with the dome dark. But not both lit. This is a bit confusing since the impulse LEDs are wired in series and should only be using 20 mA between them. So if the board is supplying 20 mA per port we should be fine but perhaps that's not enough current so somehow the N port tied into the impulse engines is stealing current from the other N port...whatever...at this stage I'm not about to try prying the B-C deck off the saucer (it's glued on with CA) to rewire the dome light so I'll just live with it. At least the dome light isn't burned out as I initially feared.