I am not experienced with MicroSeiki but am somewhat familiar with Air Bearings. Here are a few points that can help you either solve or troubleshoot your issue.
1. Air pressure constant--if your set up does not have a pressure gauge near the platter, get one and install. Platter shouldn't take a lot of air pressure to lift, but if you see it moving around, that could be an issue especially if the issue is transient.
2. Platter is level--Shouldn't normally be an issue, but i have seen with my maplenoll (80 lb lead platter), being off can lead to some occasional rubbing
3. oil or dirt on the airbearing surface--if you have a residue, sometimes it will cause sticking as the platter is getting lifted. i clean mine with Isopropyl alcohol
4. insufficient air pressure--If you can raise your pressure slightly and the problem is eliminated, then this could be the issue
5. airbearing surface damaged--i have heard that a scratch or gouge can reduce the smoothness of the platter and cause rubbing or excessive friction
6. center pin sticking--not sure how the MS are constructed, but my maplenoll has a pin that centers the platter and keeps it from moving side to side as lifted. I think from the references above, that the Micro has the equivalent it "floats" in an oil bath. A lack of lubrication here would definitely cause this issue. in the Maplenoll, i have a brass center pin that sets in a brass sleeve on one machine and a teflon pin that sets in a brass sleeve in another. but both are lubricated with a light grease. However, this is a source for friction, so check it out also
Hope this helps