There are many part-time medical assistant jobs available in New York, both in private practices and hospitals. Some job search websites you can use to find these jobs include:

1. Indeed
2. Monster
3. Glassdoor
4. LinkedIn
5. ZipRecruiter

You can also check with local medical staffing agencies or contact medical practices and hospitals in your area to inquire about any available part-time medical assistant positions. Some places to consider contacting include:

1. New York-Presbyterian Hospital
2. Mount Sinai Health System
3. Memorial Sloan Kettering Cancer Center
4. NYU Langone Health
5. Northwell Health

When applying for medical assistant jobs, make sure you have a resume that highlights your relevant skills and experience, and be prepared to provide references and undergo a background check. Good luck with your job search!