3D Printer Linear Ball Roller Bearing Slide Block Comgrow https://www.amazon.com/dp/B0728J3J9K/ref=cm_sw_r_cp_api_fMhMBbRK4R04A

But before you buy try again with what you have, only slightly hand tighten all the bearing blocks and then while sliding it back and forth, slowly tighten them to make sure it still slides beautifully