How do I remove shower handle to change stem?

It’s an old Price Pfister 3 handle shower system. The shower leaks cold water when it’s turned off.

I watched some videos and now I can’t get past the first step, pulling off the handle.

I removed the screw. Soaked the handle in white vinegar with a plastic bag and rubber band. Wiggles it. Wiggles it some more. Nothing.

Could there be anything else holding on this handle? Is there some experienced move to reduce the pressure like turning the handle all the way open before removing?