This part?
1/2-10 lead screw anti backlash nut
I’m not sure if the bolt patterns of the same but this is really close.
https://www.amazon.ca/HEASEN-Delrin-AB-nut-leadscrew-Backlash/dp/B07FFN5CTH
Langmuir will likely want a picture of the broken part but they’ll send something out.