Denny's experience with loosing retainer valves reminds me of the time I tried to assemble Walthers sprung trucks (the ones made of plastic) in a Holiday Inn outside of Cleveland (early '80s?).
I lost the springs for 3 trucks in one sitting.
I also demolished one of the chairs at the table. It broke into about 10 pieces when I sat on it. I glued it back together with Ambroid cement and it looked good enough to fool the hotel management.