I measured the outer diameter of the grommet, subtracted twice the depth of the groove, and cut the appropriate size of circle out of the strainer center ; the grommet was then fed into the hole, and a small bead of glue used to help secure the wires in place inside the groove. The smaller holes for access to the Festos were also made. at this time. Then I glued the rubber gasket to the rear face of the strainer & let everything set.