A few bleached top fan leaves

You have a magnesium Def right there . So what I would do first off is give that plant enough water to get run off and test the ph of it to make sure your in that 5.8 to 6.5 range . If your in that range then feed cal /mag . The damaged leaves will never repair but I would pull them off right away . Usually in my cases the leaves will stop getting worse then you know you have got it fixed . If they continue to get worse then you you need to keep working at it . Once you do get it under control then you can pluck them off :) Hope this helps . Also by leaving the damaged leaves on If it continues the plant has these leaves to deplete before moving onto other leaves.