D700 the problem

My old war girl is playing up recently.The problem is that it only shoots wide open on primes (That I have try )
It was displaying a Err code every time I change from wide open
Is it a cheap fix ..The shutter works perfectly when no lens is attached

cheers

Probably no answers as no one has access to your camera to fiddle around with it. Easiest solution would be to send to Nikon repair center. My guess would be broken aperture lever on the body. Unless you've got old primes that have to be locked into the smallest aperture; vaguely remember that causing troubles back in the day, but I haven't had one of those lenses in years now so that's just a shot in the dark. Cost-wise, again...no one can really give an accurate estimate short of those that work for Nikon or other authorized repair center. In my experience no camera repairs that involve going into the body and removing/replacing things are cheap.

I spoke to a nikon repairer and they mention AU$500 shutter replacement But Im thinking
perhaps electrical communication problem
cheers

Granted, I'm not an authorized repair center employee but I wouldn't have guessed shutter failure as the issue. I'd send it in for an estimate and a more accurate diagnosis.

It seems its a
Aperture Control Unit
And with it being a older unit no parts can be sourced from Nikon
What are the option?

cheers

One option is to buy a "broken" D700 for parts; assuming the parts you need are still good ... I have seen one recently on eB*y ... Then get a repair center to swap parts