I lost my regular pocket knife :( I've had a knife in my pocket for 50 years now, feel naked without it. There was an old swiss army knife in the everything drawer. None of the blades would open unless you grabbed them with a needle nose vise grip. So, I opened everything half way and tossed the knife in dilute phosphoric acid and left it overnight.
this morning it was more than loose. All the blades were floppy and the retaining springs had come out. Don't soak your knife in acid.
Karl