We have a jacuzzi filter bought in 1960. It has been working fine until now. This year it will not pull water from pool and through the system. Seem to be sucking air from somewhere but I can't figure out where it could be doing that. Any ideas?

Check o-rings, gaskets, and suction pipes and connections. Turn the pump on and use some real sudsy water in a spray bottle. Most of the time, you can see the bubbles being sucked in.
Al

The only thing that I can add to Albinfla's good post is to inspect for a crack in the housing near the strainer basket. It usually an O ring but those plastic housing sometimes crack, like after nearly a half century. You might consiedr buying a new pump and filter, they use much less power than back in the 60s.