Yelp if new and there falling out the groove was to wide to began with. But even if they don't fall out the first few times they get looser with usage
What i like is to drill the holes get a bit that is a tad smaller than the tit on the cup it will be tight at first but works a lot better. Mark your center then drill a hole just a little over 3/4 inch apart this way you can get about 19 cups per bar