Castle AT-8 Diagnostics Manual - Manual (Page 8)

3. Check the bottom frame seam to make sure it is still even. Using a clamp in this position will help
in the same way as Step #2.
4. Tighten the top four bolt bracket first, then tighten the bottom four-bolt bracket.
5. Roll the arm across the center of the table to check for smoothness.
6. Tighten the two four-bolt brackets in the middle of the frame.
7. These step may need to be repeated to get the arm to roll smoothly.