you should have around 5.5 to 6.5 volts for the lamps.
when you say "they flicker" do you mean they go bright and dim but don't turn off?
try unplugging J119 before turning the machine on in case the plugs that go to J119 and J123 have been swapped around and try it again, the little pieces of plastic that block the key holes may be missing and you may have them plugged into the wrong plugs.
J119 should have the following wires on the plug
pin1: red - green
pin2: red - green
pin3: key (no wire)
pin4: red - blue
pin5: red - blue
pin6 to pin 9: No wires
J123 should have yellow wires with a different coloured stripe on each wire going to it.
J121 is not used so it should not have anything plugged into it
the wiring code in the manual states that J123 has only 8 pins but the picture of the board shows nine pins.
If this fault has only come up after a playfield swap it possibly could just be a plug plugged into the wrong place. if the pieces of plastic that block the key holes are missing it would be quite easy to get some plugs mixed up.
I may be wrong but it's something i would check.
