@barbarajaco5700 I know you said you tapped it already but just for completion sake, here is what iRobot says
Error 9
Tap the bumper to unstick, then press CLEAN.
Constant Bump. Bumper is jammed with debris or dislodged.
So, you may have to remove that bumper which is a PITA.
There are some decent instructions about the removal [https://www.reddit.com/r/roomba/comments/l9j25c/s9_front_bumper_disassembly/|on here]