I still own my first table - a SOTA Star III in gorgeous Koa wood. Bought on consignment from original owner, circa 2007.
The platter of that era used a short, stiff rubber platter lip to create the vacuum seal. It’s not nearly as effective as the current version lips. My original platter never made a proper seal, even though the vacuum unit & hose worked fine. I had to cut it off, because records wouldn’t lay flat. So check to see if it’s actually sealing. Sending to SOTA just for new vacuum platter might not be a bad idea.
My III’s original bearing and spring suspension still worked great. I later (circa 2018) had the whole table rebuilt by SOTA into a Nova V (keeping just the Koa chassis), at significant expense. The new platter sealed properly and was a great improvement - but the new bearing, suspension, and sub chassis didn’t effect any meaning improvement IMO. In fact, the new suspension was a pain in the ass to adjust and re-adjust for a while. In hindsight, I wouldn’t have done the V rebuild - just the new platter. Maybe to a VI or VII. The newer Series VI and VII use much better materials quality than V, and could be worth it - but at even greater expense.
For the money, just a vacuum platter replacement on your III might be the most effective move.
And yes to a new belt!
As for the Jolida JD9 - I don't trust a cheap phono stage with such wild specifications. What is up with that gain!!