The top 2 strings of GI(as well as the two circuits for the playfield GI) on your backbox are going in and out the ppb board on the same connector(that is where the gi is fused) and then through the Zconnector out to the Back box. I had to replace the z connect as well as the connector at the PPB board I had it bypassing the ppb for a while which generally I wouldn't do but since it is all led's now, chances of it being a problem were nil. fun game and good price...shady seller though, what a jerk.