Play around with different positions and modifying exercises. Utilize lower weights and supersets to allow you to get a good range of motion. I.E using a incline bench, medicine ball, on knees, or sit down on the floor.
I feel like my upper back/lats improved a lot once I used less weight, higher reps, and more ROM. Heavy weights will build your overall back but it after the first couple of reps it'll be hard to get a good ROM since a whole bunch of other muscles are going to come into play.
One superset I like is some sort cable pulldown followed by db pullovers on a medicine ball. You'll need to play around with the position to really feel it in your lats. It is so much better than doing it off a bench for me.
It's hard to explain the variations but it's something along the lines of the pics below. You'll need to find the position that feels the best with a good ROM.
This free-motion machine is one of my favorites. I do several different variations by adjusting the width, and height. Then also doing it off a incline bench, on knees, seated on the floor, leaning slightly forward or back.