Issue

I have a Nikon D610 full frame DSLR camera and two lenses. One day I needed to switch lenses for different composition. I pressed the lens release button, twisted the lens and took it off the camera body. During the process I noticed something not quite right. When I pressed the lens release button I felt the button couldn’t be pressed down smoothly, there was some resistance. I still managed to press it right down and released the lens successfully. However, now the lens locking pin and the autofocus driving pin are stuck and not coming back up. Repeatedly pressing the lens release button doesn’t help at all, in fact the button itself is also half stuck. In this situation lens can be mounted on the body, but it cannot be locked, and autofocus doesn’t work. These two problematic pins are pointed out by blue arrows in the image below.

Solution

Before I took out my tools, I did a fairly thorough search on the Internet to see if anyone has come across the same issue. Unfortunately I couldn’t find any mentioning of the exact same issue that I am facing. As such I sat down and started removing the screws of the lens mount. Magic moment came at the time when I was removing the last screw. Half way twisting the screw, the stuck pins all of sudden popped back out in place! I immediately realised the pins getting stuck was because the misalignment of the lens mount and the body. As I removed the last screw of the lens mount, the mount was loosen and misalignment was rectified by the lens locking pin and the spring under it. Once I had the lens mount removed and I examined the pin hole on the mount for the lens locking pin, I can see there is very little tolerance built in.

I carefully put back all of the screws and ensure there is no misalignment again. Bingo the issue is sorted!