It is common that after market mechanisms have a different screw hole pattern from the original and therefore require adapting. A popular method is to attach a mounting board to the bottom of the chair seat. Use the original existing mounting holes to attach the board. The board should be about at least 1 1/2" wider and 1 1/2" longer than the mounting holes. If you have any hard wood, you can use 2-1" x 2" strips instead. 1" longer attachment screws or bolts are usually needed.
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.
Attach the new mechanism to the mounting board or wood using large head #14 oval head wood screw 1" long (Style #6090S). See, Mechanism placement.
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.