I wondered if the OP might have omitted some washers, the parts diagram does not show any washers between the cabinet and the top though.Quite possibly, someone has removed the washers from the bolts holding the table top on the cabinet. Adding washers isn't that difficult, but they are also used during the original factory setup to make the top flat, so if washers are already there, just add additional washers between the cabinet and top, all of equal thickness, to raise the top the needed additional height and still keep it flat. Only remove one bolt at a time, but you will need to loosen the others as well to get the washers installed. When all points have been raised the desired amount, re-calibrate the table to blade position and tighten the bolts back up. It's most important to get the blade and miter gauge slots parallel with each other, but checking the table for flatness is a good idea too. If there is a twist in the table, try removing or adding a washer to the offending corner to pull the table flat as you tighten the bolts.
My mid 80's Unisaw has this problem when some blades are installed, but not others and I haven't ever bothered to add the washers, yet. When cutting the slot in a zero clearance insert, I just use a 7 1/4" blade to make the first cut. Then switch to the desired blade that will be used with this ZCI to complete the cut. I have a different ZCI for each saw blade, since each saw blade is slightly different. I write on the bottom of the ZCI the blade that it is for, to keep from using the wrong one. I have 8 or so blades, so the same number of ZCI, plus blanks that I make aahead of time in batches of 6-8 so one is ready when I decide that the one in use has worn the slot too wide.