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Tuesday 26 December 2017 at 06:31
Do those switches have diodes on 'em?
Very meticulously recheck all those switches and make sure the correct wires are on the correct lug. If they have diodes, confirm they are oriented with the banded end on the correct lug.
Source: http://pinside.com/pinball/forum/topic/guns-and-roses-switch-matrix#post-4142856