After 20+ years of occasional searching I've finally managed to track down the door knob used on the overhead scanner lever!!

It's manufactured by Sargent. It appears to be of the Vernacular design series dating from 1888.

I found it on the antique door knobs identification website. THANKFULLY it was on the second page!! They have over 3000 knobs identified and I was afraid it would be on the second to last page with my luck.

https://www.antiquedoorknobs.us/b-10500.html

Oh well done!