I used some partial clear touch ups with some acrylic clear and it held up just ok. Painting it on by hand would be difficult. Airbrushing is the way to go but I understand it can be challenging for some. Have you thought of a playfield protector? The new types are very good and have a nice shine to them. It would also protect the touched up paint and make the playfield look like it was clear coated. I recently played a friends pin that had a protector and it looked like a new Playfield.

Is it for your Jungle Lord? It looks Like you would have to remove the upper playfield to lay down the left orbit. I would say it wouldn’t be any more difficult than a complete shop job.

Here you can see what the protector would cover.

https://www.playfield-protectors.com/Home/Details/A0NsxmlYyE6FguNCYh4t7g?catgoryid=22&name=Jungle%20Lord%20%7C%201981%20%7C%20Playfield%20Protector

These are not cheap, I just ordered one for my T2 and it came to almost $200 with plastic protectors included. But it is much cheaper than buying a new playfield or getting it clearcoated by a professional.