An all-arms jumper feels strong. That's the trap. Muscling the ball gives you the sensation of power while quietly producing a shot that's flat, short, and streaky, because the muscles doing the work were never meant to be the engine.
Where shots borrow their power
Every good jump shot borrows its power from the ground. The dip, that sink of the hips before you rise, is the borrowing. Hips drop, legs load like a spring, and when you jump, that stored energy travels up through your body and into the ball. The arm's job is direction, not distance.
Dip depth has a livable range. Sink too little and the spring never loads, so the arms take over and the shot becomes a push. Sink too far and the shot turns into two separate events (a squat, then a heave) and the rhythm dies in between. You're looking for a dip deep enough to load and quick enough to flow.
All-arms shooters almost always live on the shallow end, and most have no idea. The dip eroded gradually (casual shooting, tired sessions, the habit of firing quickly) until the legs became decoration. The tell is in the results, not the feel: shots that die on front rim, arc that flattens as the session goes on, and a range ceiling you can't push past no matter how much stronger you get.
Check the gauge
You can't feel a shallow dip, but you can measure one. How far your hips actually sink in the load is a number CoachVision reads off a side-on phone clip, and most all-arms shooters are genuinely surprised by how small theirs is.
The way back is Chair Shooting, because a chair makes the leg load non-negotiable.
Put a chair a comfortable distance from the rim: start around the free-throw line. Sit tall with the ball in your shooting pocket. Now shoot by driving up out of the chair in one continuous motion: legs push, body rises, ball rides the rise, release as you come up. You physically cannot get out of a chair without your legs doing real work, which means every rep re-teaches the feeling you've been skipping. Three sets of 10.
Pay attention to what the ball does. Most players notice immediately that the shot feels easier: same distance, less arm. That's not an illusion. That's the loan from the ground coming through for the first time in a while.
After each set, take five normal jumpers and chase that same easy feeling: hips sink, legs fire, arm steers.
Your legs have been ready to help this whole time. Three sets of ten is how you let them.