6400M - VFO "B"

On the 6400M, depressing the VFO "A" knob for 2 seconds brings up the menu, and when released, the knob pops back to its original position.  But on my radio, when I depress the VFO "B" knob to bring up the corresponding menu, the knob tends to freeze in place, without springing back to its original position when released.  I have submitted this observation to the help desk and wonder if others have encountered this.