The Dominos must fit very snugly. That is the design. Just because there are some 500's out there that might not be right, doesn't mean they all are. Having used the 500 for awhile, I appreciate the fact that the dominos fit into the slot tightly so that the alignment is always dead-on. If that means I need to scrape a ridge off the edges when humidity is higher, then it's worth it for the result. We shouldn't all suddenly feel our 500's are faulty just because the domino fits tightly in the hole. The subject of this post is an excessively tight fitting domino; one that you have difficulty even forcing into the slot.