It will work for your D7K. Here is the check list:
1, make sure M/A switch works.
a), switch to M, then you should be able manual f
b), when swtch to A, you can not turn it, may be only turn a little bit.
c), make sure it stay A, when you switch to A, If you can hear a click sound
, it will be great
2), Check the classes
a) it is easy to see front and rear elements.
b), unlock F switch, and turn F stop to F/2.8 then make lens front end
facing lights, and watch it from rear end of lens, you are able to see lens
clear or not,
c),remmber that zoom to 80, 120, 160 and 200mm and watch them in 4 zooms.
3), meet him in bookstore or some public arear, so that you have more time
to check the pictures.
Take some pictures. F2.8 Zoom 80, 120, 160, 200mm using low ISO.
F4 Zoom 80, 120, 160, 200mm using low ISO.
If you are able to load the picture to your computer, then check the
pictures in 1:1 to send the pictures..
4) Bao Zi to me, If you think those are help.....