I re-installed OS 4.5.2 and the keyboard problem remained. So I installed the oldest OS I could find, OS 4.07. IT WORKS!!!
The keyboard works perfectly again! Thank god I didn't have to get charged by a tech to do that.
This old OS doesn't have the extra banks of patch memory. I'll try to load OS 4.5.x from here and see if it works.
Thanks for the encouragement, mw7.