You can adjust the height of the sub-chassis by turning those screws at the four corners. Don't try it if you do not feel comfortable trying it. I just did a mod to my Sota that I wrote up on my system page and I talk about the springs there.
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?