I've been most careful with my AF-540 yet the tiny plastic that lifts the lock pin up still broke off (and into 3 parts too). Luckily it happened while it was out of the camera.
Looking at the design of the locking pin mechanism, I suspect there may have been too much pressure on the plastic catch (that lifts the metal pin up) when the lock lever is set at the 'unlock' position.
So maybe it is better to store the AF-540 with the lock lever set in the "fix" position, but to be safe just remove the pin anyway.