K3 autofocus not working

The auto focus on my K3 appears to be faulty and I would be grateful for any advice as to the problem before I return it for repair under warranty.
I wonder if I have an incorrect setting somewhere or have hit the wrong button!

The symptoms occur with sdm lenses and screw drive lenses but all these lenses work fine on a K5. The problem appears to be with the K3 body.
The camera tries to focus but the lenses hunt , as on a macro lens trying to focus.The diamond focus confirmation does not appear in the viewfinder if I focus manually.
I have tried the different focus modes AF, AFC and different focus AF points.
camera firmware 1.11
However it works ok in live view. I never use live view so that was a surprise when I just tried it.

I saw on the US forum a reference to cleaning the focus detector on the base of the mirror box but am a bit reluctant to do that.

I spoke to SRS who had not come across the problem and suggested a try a reset. Again I am not rushing to do that as all the lens AF adjustment settings will be lost.

Has anyone experienced this problem or can give advice for solving it.

many thanks
Paul

There are some things you can try. Factory reset is one, but first try taking out the battery, leaving it for a few minutes and then re-inserting it. Also, try cleaning body mount and lens contacts with a dry, soft cotton cloth.

Thanks John

I have tried those suggestions with no success.

Paul