After all these years struggling with MAC and never knowing about chest clearance I found this helpful video.

I also use a dry salt inhaler throughout the day, NealMed with sterile water to keep away from nasal drip, and I elevated the head of my bed 4" since I have GERDS. The last two sputum test are finally clear (off the meds). Fingers crossed.
Best to stay clear in any way that helps you to do so.
Good luck!