My chair said revise, but I do not know what they want
Your chair handed your chapter back and said "revise." You read the comment, and you do not know what they want you to change. So let us start with two honest questions. Why does your chair want you to revise, and what is it, exactly, that you do not understand?
The realistic next step is not to start rewriting. It is to go back through the feedback you were given and find where the clarity is lacking. Here is the part most students miss. That gap can come from two places, and sometimes from both at once.
The feedback itself may be unclear
Sometimes the feedback is thin, and that has nothing to do with you. There are a few common reasons. If you have moved chairs, your new chair may agree with what your previous chair already said and simply want you to follow up on that, without adding much of their own. Some chairs do not realize how much clarity a student actually needs in order to act. And a chair who is newer to the role is often still developing how thorough their written feedback is.
I will be honest about that last one, because being honest is the whole point of writing these. When I first started chairing, right around ten years ago, I was a beginner, and my feedback was not as thorough as it is now. Today it is obsessively thorough compared to what it was back then. That does not make a newer chair unable to help you. It just means the clarity you need may not have made it onto the page yet.
Or the gap may be in your own understanding
The other side is the one students are hardest on themselves about. You are a novice researcher. You are overwhelmed by the whole process, not only this one chapter. Many students open their document, see how many comments came back, and go into a kind of shock. Then they freeze, unsure what step to take next. That is not a sign that you do not belong here. That is a normal reaction to a hard and unfamiliar process.
Why this matters
When that clarity is missing, from either side, it affects you. Students walk away from vague feedback feeling less confident, stressed, and overwhelmed, and that weight is heavier in a rigorous program. The danger is not that you cannot revise. The danger is that you lose momentum while you sit there guessing, and momentum is the thing that carries you to the finish.
How to tell which gap you are facing
So the real question to answer is this. Is the problem in the feedback, or in my own understanding of where my writing stands? You will not solve that by rereading the same comment ten times. You need a clear read on your own chapter, and that is what a dissertation diagnostic gives you.
Let me be clear about what this is, because it matters. A dissertation diagnostic does not write your dissertation for you. It is for students who have already done the hard work, the writing, and now have gaps, alignment issues, or clarity issues inside the document. When you run your chapter through ABD2DR, it finds those issues, tells you where each one is, why it is a concern, and gives you a suggestion you can act on. Once you can see that, the fog lifts. You know whether the gap was in the feedback or in your own understanding, and you know your next step.
You can test it first with 500 words of your own chapter, just to see how it works. That sends your feedback back as text. The full review goes further. The feedback comes inside your document as track changes, the same way your professor should give it to you.
You have already done the writing. You do not have to sit in the fog, guessing at a one-word comment. Catch it early.