Pulled cluster - now dash lights don't work

If there is a good bulb in the sockets it completes the circuit so all could grond at just one screw. Ablown bulb would interupt the path. Regardless, nothing is chassis grounded unless there is a chassis ground path.
The best path is an actual copper wire attached anywhere. If it is connedted at only one of those bulb screws, that bulb may burn a tad brighter or a lot brighter than all others.
To run a small wire from every screw is a lot of trouble.