Adding this small amount of wood thickness under the seat does not usually cause any problem. However, because of the added wood thickness the chair seat may not to go quite as low as it once did due to the added wood. If that is a problem, please call for instruction.
Should new mechanism screws or bolt position interfere with mounting board attachment, countersink or counterbore them. Do not install new mechanism screws any closer than 1/2" to the mounting board screws. Further is better.
Curved bottom seating:
If your chair seat bottom is curved preventing the mechanism from lying flat to the attachment holes, call or email Contact for an easy fix.