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Maybe use a higher resolution to print the bearing lock in washer if you have not tried this yet. If it is too tight fitting, maybe scale down the washer just a fraction and re-print. The hole in the top and bottom was in case it is needed to be locked (no spin). A pin of some sort can be inserted to lock the top to the bottom sections. If there is too much gap between the top and bottom where the balls fall out, then something is surly wrong. It is more then likely the spacer that sits on the bearing before the top in put on. It sounds like it is too tall for some reason. It should provide just enough clearance between the top section and the actual bearings. The top should just be touching the ball bearings. The top section revolves around the inner section of the bearing, so the bolt and the top section should all spin together. Also note that just spinning the top on its own will not provide a lot of spin. The weight of the ball is needed. Hope this helps. Enjoy!