Epson 850Z diopter adjustment

When I tried to change the viewfinder diopter control, it seemed very stiff and ineffective. After reading more in the manual I saw the warning not to attempt this adjustment with the power off. The camera must me powered up before changing the diopter adjustment. Now, after turning on the camera, the diopter control seems just as bad. I suspect I may have damaged it.

The lack of a diopter control does not bother me, but it may be connected with some more important mechanism. Any opinions?