Question about replacing rubber gasket in Kohler flush valve

I have a factory flush valve in a Kohler toilet.

Pic: https://m.imgur.com/a/yf3YP

Of the parts in the center of the tank, the outer cylinder has a red rubber gasket/seal at the bottom. This seal gets displaced when flushing, causing the refilling water to continually flow down into the tank.

Is it possible to replace only this gasket? Does this kind of valve have a name that I can search for on youtube? It's not immediately apparent whether this is something that can be disassembled.

Thank you.