Check slipping headrest motor

[Momo]

I would like to see whether I can fix the slipping headrest adjustment in my orthopedic seats. (The motor operates fine, but does not move the headrest up unless I help. It moves it down OK.) There is a sort of cover over the top of the assembly, starting just above the lever that releases the seat back. I have removed the plastic cover immediately under the lever. The top part of the cover that covers the motor assembly and seat belt anchor point is happy to come away, but not the bottom part. I do not want to force the bottom part. I can't see any screw or other item that might need to be undone. Should I just pull harder?

(I will post a photo tomorrow, if this is not clear enough.)

Momo