I use only plastic now and will never go back. Yes adding more wax will get them drawn out faster. I use a cheap double boiler that you can get at Wal-Mart for about ten bucks. And a single burner electric hot plate. Melt the wax and brush it on with a paint brush.
For the wax moth infested frames scrap them off I found using my uncapping knife works easier than a scraper. I use to pressure washer them ( another good thing about plastic. Try that with wax) but found it don’t really matter. Brush more wax on them for better results.
Sounds like you found a real gold nugget at that garage sale!
The Busy Bee teaches two lessons: One is not to be idle and the other is not to get stung.