Hi Trevor, the last nikon prime lens cell I dismantled had 2 very very tiny Phillips head screws which need to be removed then the lens cell could be unscrewed. I had to use 2 strap-wrenches to get a grip on it.
Hi Matt, and thanks for that. The lens is the 180 F2.8 AF ED Mk 1. Apparently the Mk 2, the more recent, is a slightly different lens configuration.
It has a spot of tropical fungus between the lenses, and since it was a freebie it seemed worth the adventure to clean it.