Good morning @sharonednaramsey,
First off, are you nebulizing with saline? That is a must.
Second, I think most folks here will say they have had to experiment because everyone's bronchiectasis and/or MAC is different. Different severity, different locations in the lungs.
I could only get up enough phlegm for testing after seeing a respiratory therapist (or as my doctors prefer "chest therapist").
My aerobika did nothing, postural therapy did nothing, but saline nebulizing + smartvest are successful. Mixed results with vests among folks here but more than a few have good results.