I am going to repaint the five doorframes in my hallway. The previous paint job from about ten years ago has way too many brush marks and drips. I started sanding, and it seems like the previous painter did not do a good prep job. The top layer of paint didn't adhere well, although not poorly enough to remove easily. I know I need to get that layer off and sand things smooth. It is very labor intensive hand sanding. Are there any alternatives? Could I use a stripper without going all the way down to bare wood (worried about stripper residue).

Here's a photo to show the profile I'm working with. Bullnosed plaster. Not big enough surfaces for my orbital sander.

Thanks for any ideas.