I think that may be the problem.warped baseplates. I have new baseplates from union on the way as well as a conversion discs from burton. if none of this works I am finished with union because I will ditch union bindings before i ditch burton boards.
If it doesn't work at least you tried everything possible to fix it. I hope everything works out and you can avoid shelling out the scratch for new bindings. On a high not, if you end up getting new bindings and go with burton EST you will get the full benefit if the EST system.