Stair Hand Railing

I am trying to draw the balusters on the hand railing. Every time I draw on the angled hand rail plane that starts from the ground to the landing, it wants to stay on that angle. How do I draw them perfectly vertical then using the linear pattern to equally space them? I know there’s an easier way than one at a time. I appreciate the help!

Drag the pattern tool’s gizmo’s midpoint to the rail’s plane, then when you use the arrows on it it will stay on that plane / angle.