Got me stumped i'm afraid, i haven't had this issue with my machine in the time i've owned it. So they work any time other than after mystery slot is awarded? wouldn't think that would be a connector or opto issue if the reels are good in test. Just a weird thought here, wondering if the game Rom chip is a little loose in it's socket? it's a long shot i know but i can't think of anything else at the moment. Ive had weird opto issues on a JD machine before but this is different altogether.