Disagree completely with that advice. Glycolic acid works fine if you use it right and don't overdo it. The problem was probably the strength or how often it was used, not the acid itself.

Totally get that feeling. My old cheap pair had the same random cutouts, especially outside. Ended up grabbing some Soundpeats on sale for around fifty bucks, and the connection is just rock solid now, plus the battery lasts forever.

Did you catch that segment on local news about chimney safety checks? I read a whole thing from a fire chief saying amateur cleaning often misses the deep creosote pockets. @oliviabennett has the right idea hiring a pro, because they do more than just brush it out. They can see problems we'd never notice, like hidden cracks or nests. From what I've heard, that creosote is way more flammable than people realize. Skipping a real cleaning is like betting your house on a guess, and that's a bad bet.