OK. I deleted both using CUPS. Then I used CUPS to reinstall. CUPS gives three choices of driver.
HP Officejet Pro 8500 a909a (en)
HP Officejet Pro 8500 a909a hpijs 3.9.8.36 (en)
HP Officejet Pro 8500 a909a, hpcups 3.9.8 (en)
the hpcups driver won’t even print a test page.
The other two print a test page that is shifted down slightly.
They both print PDF files with the top .2 cm missing.