Not familiar with that valve but I can't believe gaskets are not replaceable. Only one I'm familiar with is mine, a Hayward. The gasket is glued in place and to remove the old one you destroy it by chipping and scraping the channels that it sits in. Once the channels are cleaned you can install a new gasket. Lot of debate on the forum about how to install a new gasket. If it comes to that, replacing, I can tell you what worked for me. Others disagree on the technique and will certainly chime in.
Al