Tue 01-Jan-13 04:17 AM | edited Tue 01-Jan-13 04:19 AM by Bravozulu
This may not answer your question, but I too was having trouble with my HB-39 hood. When fitted to the 16-85mm lens, it wouldn't click in when attached and rotated.
I live 10 miles from the West Coast Nikon repair center and took it there. One of the technicians looked at the lens and hood and, together, we agreed that a tiny drop of epoxy glue applied to the cam points on the flexible inner ring (of the hood) might provide enough of a friction point to solve the problem. Of course after the epoxy had dried.
I went home and did this on the two high points, using a toothpick to apply the epoxy. It worked. And it saved me $30.
In actual use, the lens hood gets banged and shoved. Mine dropped off without me knowing at a car show. I retraced my steps and found it. Luckily. That's why I wanted a tighter grip when mounted.
Some of the vendors in Hong Kong you'll find on eBay carry genuine Nikon branded items at cheap prices.