How to segment part of one object

Thanks for your great work! I want to segment the (end-effector)gripper of a robot. But I tried different text prompt and I can not get an ideal one. <img width="821" height="820" alt="Image" src="https://github.com/user-attachments/assets/d745b506-bfcc-4658-ba85-8cf020b5661a" />  Do you have any suggestions to help me solve this issue?