The A and D strings on my bass buzz at the bridge.  When I touch the strings between the bridge and tailpiece it stops buzzing. I'm thinking maybe the saddle cuts aren't right for these strings and the strings are vibrating in the saddles causing the buzz, but not sure if this is what's causing the issue.  The bridge is the old 70s Stars Guitars type. Any other thought is suggestions for how to resolve this? Thanks.

Try turning the intonation screws to take out any slack/slop that might be creating a little rattle first Rob. While you're at it, might as well check the intonation with a good tuner.

Failing that, a slot may need to be angled carefully back towards the tailpiece, not necessarily deepened. That can be the source of a little rattle too.

Loose wire?
If it's a Series instrument, perhaps no batteries attached to the clips?
If you have a strap with straplocks, but you're playing sitting down with the strap not carrying the weight of the bass?

I'll add two things.  While unlikely, check that the strings aren't touching the back rail of the bridge.  And, while keeping in mind Greg's caution to not deepen the slots, you might want to check for any roughness in the slots.

Thank you for the suggestions, I will investigate as suggested 😊

I turned the saddle screws moving the saddles back and forth, lightly sanded the saddle grooves with fine sand paper, and reset the intonation.  The bass is now completely buzz-free.  Thank you!! 😊