"When was my accordion made?" seems to be a common question, so how about we accumulate a list of outward indicators of age. Not rhinestones or missing parts, but more like; When did the stepped CBA keyboard first appear? When did the Pearloid finish first appear? When did box shapes transition from "square and boxy" to "rounded and svelt"? When did the current register switch marking system [Circle with 2 horizontal lines and indicator dots] appear vs. the practice of naming registers by their similarity to other instruments. What time span were "waterfall keys" produced? Evolution of keyboard shapes? And so on. While not finite, this would be a useful tool to get close to an instruments era.
Press on....
Waldo
Press on....
Waldo
