After years of use my phenolic router table top has developed quite a bit of sag in the center both front to back and side to side. The Rout R Lift will just not sit flat and flush with the top anymore no matter how it is adjusted. I have a heavy 3 3/4 Hp 220V router mounted in it. I tried shimming it in the center of each side between the top and the square tubed aluminum stand and tightening down the corners to pull the warp out to no avail. Is there a cast iron top out there that will accommodate the JessEm/Powermatic Rout R Lift?