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Tuesday 16 January 2018 at 01:30
that's when it's most obvious: when it goes yellow/orange, the left side is red. i know you mentioned the green might be flaky, and i don't really know how these work, but the green color looks fine when it comes up.
Source: http://pinside.com/pinball/forum/topic/official-tron-lovefest-thread-i-love-it-more-than-lamp/page/149#post-4178016