My lovely contax distagon 35mm encountered a little problem recently.

The front end of the lens barrel (in red) is moving a bit, up and down.

http://farm9.staticflickr.com/8365/8456793207_327589592f.jpg


It is only the barrel that moves so it doesn't affect photo quality and focusing.

I searched the web about adjusting infinity focus of the lens because it has a bit of focusing issue on my 5Dmk2.

and found the screws under the focusing ring wrap.

There were screws placed around the ring for adjusting the infinity focus but another 2 vertical ones (which I do not have a clue what do they do) and it seems it has been loosened before, little marks are seen in the picture.

http://farm9.staticflickr.com/8091/8456793233_6f3db92acb.jpg

Anybody know how to fix this situation or encountered this problem before?

Thanks in advance.:(