For mine I swear all the shop did was clean it up and renew the damping grease on the focus mechanism. Even with loosenesss and "rattle" I never experienced an affect on image sharpness.
That sounds promising. If the issue doesn't effect the sharpness, then I can live with it for a while. It's still in E+++ shape, and it looks like it's holding it's value, so it would be worth spending the $$ at some point to fix it.
BTW, the only "value" a lens has for me is its ability to produce images. :)
i took mine to Ray's Camera, located in the Denver Pro Photo shop.
He revived my nearly dead Nikkor 35mm F/2 AI. The barrel was loose, the focus action was inconsistent and squeeky, and the focusing ring rubber grip had disintegrated. He tightened and lubricated everything, and found a rubber ring for my lens. Other than the worn off paint, the lens performed as if new! He had told me on several occassions that I should just junk it, rather than shell out the money to fix it...but then I showed him the prices of a decent 35mm f2 AI. I loved that lens AFTER he repaired it.
I like Ray for all of my Nikon stuff. (which I no longer own...now that I have a Contax G2)
I've just looked at some 100% crops from DX images using a D5100 and that 28mm F/2. Nothing appears amiss, either focused at infinity or at the closest distance of 0.25 meters. In fact, I'm damn pleased with what I see. If I were shooting Kodachrome or Velvia or a new Ektachrome or techpan or something like that, on a tripod, with the mirror locked up, I might, might, give the nod to the f/2.8. But I shoot Tri-X so it's a non-starter. Plus I like that extra stop and the veiling at f/2. I've never been inclined to pixel peep and I'm less so every time I conduct one of these (for me) pointless little tests.
I still don't like that rattle but it doesn't appear to be causing any problems. For me. YMMV. Good luck and post if you take any action and what the outcome is.