Hi nrbristow,
Thank you for using the Support Forum. You have done the things I would have suggested. One other thing you can try is remove the drum turn the machine off. Turn the machine back on with the drum still out of the machine. Wait for the error to display and then install the drum again. If the message still does not clear please consider contacting your support centre for further assistance.
The WorkCentre 6515 is giving me an error that the Yellow Drum cartridge is not installed correctly. It shows a message on the screen to reinsert the drum with a code 091-927 in the bottom corner. I have done that multiple times with no change. I even tried to remove the old cartridge and install a new cartridge and still got no change. Is there something else I should look at?