My OMNI 1530 has been up and running for about a month now. A few days ago I tried to resurface my spoil board and the depth was all over the place. The bit was slowly sinking deeper over the first half of the table and then suddenly raised back up fairly quickly. I've seen this same pattern as I've run parts since then. I suspect it's the spindle that's the source of the problem (and not the vacuum). There appears to be a pressure regulator for the spindle, but the manual from OMNI does not provide any instructions on what to set it at. Currently, it's set very low (almost to zero).