Campagnolo Exa Drive

I could use some advice/help/information. Just picked up a Mandaric road bike with a mix of Campy components. The cassette is 8 speed Exa Drive. The freehub is not. It doesn't have the one narrow space. The chain skips under hard pedal pressure. Wondering if it's just off/loose enough on the freehub to cause this skipping. Cassette and chain seem fine it slightly worn. Teeth all look okay. Any help would be appreciated. Thanks!