I'm not a hardware guy (so please correct if I'm wrong...seriously), but if it's just that one instruction that has unknown functionality, couldn't they look at the code and the specified functionality (of all the code) and sort of reverse engineer the logic of it? Or find one of the old computers (in a museum or something) and examine the hardware in it?
They'd have to unwrap the instructions (hard-wire, literally) to get to the meat of it, and even then there's no guarantee they'd be able to put it all back together again.
Better that it just remains curious, and that we don't use AGC Version 1.0 for future launch attempts ..
