Today the spoilboards were removed, the plenum below was milled flat and regrooved, the 6 individual spoilboards were reinstalled with double stick tape, and then the complete table was skinned to be flat and true (with the vacuum pump turned on) . The spoilboard may or may not be the same height with the vacuum pump off because I am testing 3 different types of double sided tape and the tapes are different thicknesses.
For your information the 6 zones are numbered 1,2 &3 on the right side going from front to back. The left side is 4, 5 & 6. Until the new valves are delivered and installed, only zone 6 (back left corner) has a valve. You should keep this valve closed anytime you are not using that back left corner. Doing so will maximize your holddown force in the other 5 zones.
I left instructions to users on the board, but we really need to think and act on a plan to educate users how to use the system ASAP. It’s not much fun replacing spoilboards!
Oh, and I recovered another 0.15" of Z-height. Net loss is 1/4" compared to the original installation.