Cool trick I saw on YouTube about filling the fret slot ends with melted crayon.
Before:
https://uploads.tapatalk-cdn.com/201...762d545aac.jpg
After:
https://uploads.tapatalk-cdn.com/201...f6e59f05a5.jpg
Quick easy and works well. Just melt the tip of the crayon, rub it into the slot. Once it's dry, just scrape off the excess with a blade.