Did it feel like typing on a bag of angry crickets?

Honestly, lighter fluid is a solid pick because it's mostly naptha anyway. For really stubborn helicoids, I've had good luck with a 50/50 mix of automatic transmission fluid and acetone. It's thin enough to creep but leaves a tiny bit of lubrication behind so it's not totally dry when you start working it loose. The key is letting it sit for a couple days, working the mechanism just a tiny bit each day to help it along. Straight acetone can work faster but it dries out any remaining grease completely, which can lead to scoring if you force it.