What are the chances that a loose race would be causing the judder?
High. It's basically the same as having excessive bearing clearance.
What sort of headset? If it's a cartridge bearing, you might get away with a split crown race as long as the clearance is small enough to be taken up by the inner bearing compressing the conical seat radially without bottoming out axially.
Wolf Tooth premium, cartridge bearing. Annoyingly no one seems to have the replacement crown race in stock in this country, only the full lower assembly.
High. It's basically the same as having excessive bearing clearance.
What sort of headset? If it's a cartridge bearing, you might get away with a split crown race as long as the clearance is small enough to be taken up by the inner bearing compressing the conical seat radially without bottoming out axially.