@lewm Ah yes! That was an observation that others had about the early tables. I do remember one reviewer mentioning this also, and he found the best setting for him was 1/3 of the dial on vacuum pressure.
The new tables do not allow you to adjust pressure, there is a factory algorithm followed. There is an initial pressure applied to clamp the record and seal it, and then it is reduced to a maintenance level. On my Cosmos you have to remove the air hose to get the table to play without vacuum and I did that early on. I never noticed a degradation due to the clamping of the record, if anything I achieved improved resolution and fine detail in playback. I am satisfied with how the system works.