Testing a $9/mo onboarding call on my paid newsletter

My challenge is manual onboarding — every new paid subscriber gets a personal welcome from me, and it's not scaling. So I'm testing whether charging for a 15-minute onboarding call filters out tire-kickers and gives new subscribers something useful enough to reduce churn. I ran it on the last 20 sign-ups. It helped, but not in the way I expected: the call didn't reduce my time, it just made the conversations better. Now I'm deciding whether to keep it at $9 or drop it to free and cap the calls per week.