While perusing the DPreview m43 forums, I came across yet another person complaining that their 12-40 pro have came apart at the mount due to failure of the plastic screw mounts for the rear bayonet.
I instinctively decided to test my 12-40 on my EM1 to see if there was any pull play on the mount, and to my astonishment the lens flexed and started to come apart!!! It seems my 12-40 lens is only being attached to the bayonet via the top screw and the rest must have failed which has allowed the lens to flex.
My E-M1 and 12-40 pro combo is just over a year old now, and I never realized to check for this issue!
From what I read, the 12-40 pro lens is extremely fragile, and should not be subjected to any side forces when mounted on the camera. Some say it is batch related where from factory they screws are over tightened and hence the weakened screw screw mounts.
The strange thing is Lens rentals has established that many other pro grade Canon and Nikon lenses also use plastic screw mounts for their bayonets and have not as much failures as they have had with the 12-40 pro.
This does not give me much confidence if I cannot even leave my camera straped around my neck, as the 12-40 lens will protrude outwards and will bump into things gently from time to time.
Has anyone here experienced their 12-40 mounts failing due to the plastic screw mounts? If not, it may be possible you may not have tested pulling your lens away from the mount while mounted on camera, as that is not something one does normally, and one can quite possible not realize their mount screws have partially failed.