Pentair O-Ring For Rotor O-27 S/M MPV

The two O-rings fit in grooves in the shaft of the rotor on the selector for the American Multiport valve. They are installed by stretching them over the end of the shaft and pushing them down the shaft to their respective grooves. These O-rings stretched during this process enough that they would not seat tightly in their grooves so that the shaft would not slide into the bore in the valve lid without carefully working each O-ring into its groove while pressing the shaft into the bore. I did this first without the spring in place to let the O-rings acclimate for 24 hours hoping the rubber would contract to fit snugly. This did not happen. While assembling the system with the spring in place I had to reach between the spring winds with a small screw driver to tuck the slack into the groove on each O-ring while using two trigger clamps to slowly compress the spring and push the shaft into the bore. This process was extremely tedious. If these are new O-rings, they should certainly have enough elasticity to spring back tightly into their grooves after sliding them down the shaft. Before starting the installation I greased them well with silicone lubricant. At least the valve does not leak at the shaft after reassembly.