Quote Originally Posted by AgX View Post
In the manual I found this:

The New F- 1 has a built-in safety circuit which prevents shutter release if the lens aperture ring is on ~the "A" mark and a power drive is not attached.

Enigmatic to me...

but maybe useful to you.
I never realized that, but it makes sense. The New F-1 is an aperture priority camera, so you never have the aperture ring set to A. When a power drive is attached then shutter priority is enabled.