On the hip-rotator machine, the resistance helps you load your hip rotators — seated with one leg extended onto the support pad, rotating through the hip.
On the leg press, strengthen the hip capsule's ability to rotate internally — feet on the footplate, legs bent, driving the knees toward internal rotation.
Stronger hip capsules mean less back compensation — your lower back stops making up for a hip that can't rotate, so rotation feels freer and pain subsides.