We took away all the screws, and made the jacks ride freely in the guides, either by enlarging the slots in the lower guide, or by tapering the jacks. We still have the screws, and we'd love to sell them to someone. But not for use in harpsichords. The old builders knew what they were doing. While we were at it, we got rid of the screw-threads on our tuning pins.
Screws are wonderful things.
Wouldn't want to make a watch without them. But they do nothing for harpsichords, save to screw up the action.