I don’t think lat pull downs are working for me. Then again it might be my technique and not enough weights like you think. But if its one thing I have been told ‘Technique is everything’ and I try to stick by this.
I see a lot of people doing these as a sort of low back/rear delt combo exercise.
More likely to be using to much weight rather than to little.
First as Bodytek suggests try pushing your elbows forward, this will also stop you leaning back. Keep your back vertical. Pull the bar to your chest. Wide grip palms forward so you take bis out as much as possible.
If you can’t get your reps through pull ups start with pullups, move straight to pull downs then polish off with lying or standing pull overs.