I would clean it all out first before repainting it bro. Goof off and an old toothbrush will clean out all the markers nicely. Most aftermarket inserts are full of white paint and have to be dug out with a needle.
When spraying, apply very thin coats, a few seconds apart. Use the least amount of spray possible on each pass. I apply a good amount of paint maybe 8 or 10 thin bursts of spray. Alternate directions of spray to get complete coverage.
You’re a wealth of knowledge and am grateful RWI has the likes of you and others! Great advice, I will do this, will follow up with pics.