German WWII Luftwaffe Gravity Knife, Take Down Model, RB Numbered

Original period manufacture. 2nd model knife, take-down pattern, unmarked blade, with a RB numbered marlin spike. The knife shows age and use, the springs are not broken and they function as they should. Minor cleaned corrosion pitting to the metal surfaces, but all in all it's a pretty honest old knife. I can depress the unlock button but I couldn't removed the grip cap/blade guide.