Why can't I increase the weight on my barbell row?

If you are really determined to increase the weight, I would try increasing the weight and have someone give you “help” to get the weight up a few times and within a week you should have it on your own.

Wear forearm support bands to help prevent a really bad “tennis elbow” injury too or just listen to your body….the pain is telling you you are over doing it.

Also try not to get a head of yourself, mainly focus on not injuring your back… too much too soon could be detrimental to your workouts….. :-/
Take it easy….. slow progress is better than none at all….......

Are you using lifting straps? They take the weakest link – your fingers – out of the equation…

Is the weight that you’re using for the lat pull downs less than, equal to, or greater than your body weight?

If it’s less than, then I suggest trying to do pull ups on an overhead bar.

If it’s equal to or greater than, are you using any anchoring or are you actually doing pull ups on the pull-down bars?

Depending on the rep range, it’s right around my bodyweight. The machine has an anchoring device that locks my knees in place. I can do about twelve pull ups in a set, but I prefer the machine because it allows me flexibility with my routine as far as drop sets and rep ranges go.

@quarkquarkquark

“The machine has an anchoring device that locks my knees in place. I can do about twelve pull ups in a set….”

How about doing fewer reps with more weight? Once you get to your “struggle rep”, do what I would call peak isometric reps, where you apply isometric force to the stopping point in your motion for about 3 breaths.
I added 30 pounds to my bench press in about a month using that method.

How much of your back are you using for your bb rows? Are you using a bench to support your torso weight?

@Brian1946, the isometric idea is a good one. I do not use a device to support myself when I do rows, but I did read today that the problem might be that I keep my back at too obtuse an angle. That is to say, not close enough to parallel to the floor. Does that sound like it could be a problem?

@quarkquarkquark

“That is to say, not close enough to parallel to the floor. Does that sound like it could be a problem?”

Could be.
Do you do any exercises to strengthen your lower back?

None specifically. I am a big proponent of compound exercises, so my workouts typically consist of four big compound lifts (typically with barbells, although I substitute db bench for “regular” bench) and two or three isolation lifts that I switch up every workout. I also change rep schemes on a regular basis. My only lower/middle back work comes from rows, pulldowns, occasional chins/pull-ups, decline crunches (which I want to stop doing because I’ve heard it can be harmful) and hanging knee raises.

Okay, then try doing some lower back curls on the days that hitherto put the least amount of stress on your lower back.

My reasoning is that if you specifically strengthen your lower back, then you’ll eventually be able to lift more weight with the bb rows.

I have heard that lower back curls are actually detrimental to spinal health—what do you know about that?

That could depend on how much you extend or crunch them.
A chiropractor recommended them to me.
You might want to consult a chiropractor or trainer before doing them.

I do them lying flat on my stomach, and arching my back to a point short of where my spine is blocking any further arching.
I’ve been doing them like that for almost 24 years without comprising my spinal health.