spigot leak

I have a vacuum breaker on my spigot in the backyard. When you turn off the spigot it sprays water. Not dripping, not a little spurt, but high pressure spraying from the hose side of the vacuum breaker. Once the water is completely off, and the pressure has died off from the hose, it stops...

I have a frost free spigot with a damaged plunger part that is causing water to leak out the drain hole when the spigot is shut off. It's the cylinder located inside the handle. Does anybody know what this part is called and if it can be replaced? Thanks. https://ibb.co/bxnSQ6