Does anyone know how to remove the adjustable head restraints at the top of the front seats on a late 1992 VP Series 2. I need to get them off to fit new seat covers. I cannot find any buttons, release catches, etc on the outside of the seat tops. The 2 chrome sliding head restraint support rails on each seat just disappear into the fabric seat backs via black plastic grommet lined holes.

Thanks - hope someone knows how to do this.