I have come across at least three if not four variations of how the bearings in the table are attached / adjusted. There are both 3 sets of bearings and 4 sets of bearing variants as well as adjustable and none adjustable variants.
The procedure to set them up is the same for all apart from the none adjustable variant, however how you adjust them does vary. You need a large engineers square, something to accurately measure a reference height such as a clock and a parallel. (Can be an accurately planed piece of timber but an engineers parallel is best)
I remove the parallel bars with the table attached by removing the 4 cap headed bolts that secure the cast iron ends that hold the bars and secure them down to the frame of the machine. Make sure the grub screws holding the bars int9 the cast iron ends are tight. When lifting it all off one at either end is a good idea along with securing the table to one end.
Note 1: the fence is pinned to the table, so unless it’s bent, it can be set true to the bars.
Note 2: the column that supports the heads is pinned to the frame. Unless the frame has been bent (which I’ve seen) it should be vertical to the bars and the bars perpendicular to it.
1. Place the parallel on the two bars, measure the height of the table to the parallel at all four corners. Adjust the bearing cam that holds the bearing that touches the top of each bar until all 4 corners are the same height from the parallel.
2. place the square on a rail and check that the front edge of the sliding table is sqaure and true (assuming that the fence is square and true to the table. If not use an adjustable square to measure how far out the fence is and use this as the defence for the side of the table.
now adjust the bearings that touch the sides of the bars to move the table into true.
3. Repeat steps 1 & 2 until no further deviation is seen. By adjusting the side movement of the table you can affect where the top bearing is touching the bar.
If you have a variant that isn’t adjustable and the table is out, remove the blocks from the table that hold the bearing / spindles. Mark up each location and each block. Create a table with every permutation of where the blocks can be positioned (either 9 or 16 locations depending on whether you have 3 or 4 blocks) now go through the process of attaching the blocks in each sequence and checking with a parallel and square as in 1 & 2 above to see if the table comes true. It will on one permutation, if your lucky it the first you try!
I’m sorry, I don’t have any photos of the underside of the tables to show all the variant.