Unpopular opinion: the lighter fluid trick on a stuck focus ring actually worked
Had a customer's 1980s zoom lens come in last Tuesday with a focus ring frozen so tight I was sure it was cross threaded, and after two days of soaking in the usual solvent I tried a single drop of lighter fluid worked into the seam with a toothpick. It sat overnight, and by morning the ring turned smooth as new with no damage to the rubber or the markings. Has anyone else tried this on old rubber gripped rings, or am I asking for trouble down the road?