your correct in your thinking about the four hex screws. You can soften or harden the suspension on the SOTA table by adjusting it by turning the hex screws. Turn them slowly until suspension has a proper feel or bounce using a spirit level. I'm sure there is much info on this table with a more comprehensive instruct tuning the unit to an optimum performance level. The best its a good table.
To adjust ride level of springs on SOTA turntable
I have an older SOTA and the sub-chassis rides about 3/16" below the outer cabinet. I noticed there's screws that I assume can be adjusted to tighten or loosen the springs, is this the way to change the height of the sub-chassis or are the springs just old?