First follow the instructions to remove the rear wheel:
https://drive.google.com/file/d/1HcEqBWW7wPUJ_769Ynaom6YZXet6uy9P/view?usp=sharing
Then check out this video that addresses the arm replacement:
https://drive.google.com/file/d/14E4Uu8PAyD5fmXIkL8JdcNqMkv3XVBMr/view?usp=sharing