Simmering the bones for broth is a technique I learned from an old Julia Child episode. She called it the foundation of avoiding waste and building flavor.

Wasn't there a whole thread on Reddit's typewriter forum about using citric acid solutions on stubborn mechanisms? I remember someone swearing by a weak lemon juice mix for freeing up sticky keys, but they emphasized rinsing it thoroughly. The consensus seemed to be that modern mild acids are less corrosive than the old warnings assume. Maybe those guidelines were based on harsher chemicals from decades ago.