Pentax 645N focus beeper

[JCJackson]

I just picked up a used Pentax 645N with 75mm autofocus lens. All seems to work as intended, with exception of the audible "beep" that is supposed to signal that critical focus has been reached in either manual or auto mode. Yes, I have the power switch in the middle position, which should turn the beeper function on. Does anyone have any experience with this problem on these cameras?

 

[telkwa]

It works on all my manual focus lenses; I don't have any FA.