Thank you for all the research you have done for me.? It is a big help.? I downloaded the manual so I am all set to search for the part.? I agree with you that the rigs must have been mishandled, in the same unfortunate way.?
I checked eBay and HiFiSSB sites.? No such parts.? HiFiSSB does not have this rig model on their list.? So the hope is that someone, perhaps on this list (yes, right now it is fairly thin but may grow over time) is parting a radio.? If you hear of someone doing so please let me know.
In the meantime I shall search similar-sounding models like the '990.? Maybe there is some part commonality.? I will also contact Yaesu parts and see what they say.
N4PL