OK, I believe I have gotten the gist of fine tuning. This is going to be a little more complicated as I need to provide a little more background.
My lenses and camera were working fine until a couple of months ago when I was video recording my son's band performance. Half way through the performance, the unit locked on me. I had to remove batteries and reboot to start. The back screen no longer worked and was getting the err message. After searching web for answers and finding nothing, went to JustAnswer.com and got a camera specialist who ran me through a series of tests, which I did, and told me my main board was fried and basically said I'd be better off buying a new camera body than trying to get it fixed. Well, that's a little too much for me, so picked up a main board on Ebay "new" from China. The "new" board looked ok. I installed it and eventually got it working, the main screen was working. At first, actually, got the Err message until I opened the unit to inspect and open the mirror and magically the err disappeared and the unit appeared to be working properly. Thought I was out of the woods until this VF focus thing bit me. OK, results of testing.
On my nikon 18-200 lens, which I love, -20 produced the best result, but was still quite blurry. I switched over to my 18-55 lens and got a pretty decent result at -20. Before it was at 0.
So, why would switching out a board change the focus parameters through the VF, which to me appears to be what happened?
Next, am I hosed? Anything else I can do without spending hundreds to get this focus thing fixed?