J. Edwards , Sep 06, 2011; 10:22 a.m.
I had a CHA error that would appear rather randomly on my D70. The battery would drain, and I thought the batteries themselves were the problem, I replaced them and still got the error. I tried cleaning the contacts myself, it didn't help. I took it to a local repair shop, they nodded and said it was a known electrical problem. They sent it to Nikon for the repair. It's worked flawlessly since then. However, it did cost me about somewhere in the neighborhood of $200-250. A few years ago that was on the edge of not being worth it, but now it's really probably not worth it to fix it for that cost.
Unfortunately I can't help you with your lens problem, sorry!