Hi Craig,
Save yourself a trip to the garage ...
The locks do need lubricating periodically, or it becomes difficult to insert and retract the key, meaning that you end up using excessive force and potentially inadvertently removing or damaging the lock.
As with all mechanical components, there are different schools of thought as to what type of lubricant to use, be it oil, silicon or petroleum (WD-40) based. Either way, if you just apply plenty of your preferred substance to the key and then push the key in an out a few times and lock and unlock the door it will make a world of difference. Also, if there has been a lot of friction within the pins, you may well find that the front disc face of the lock has become distorted and is no longer flat. This will also prevent the protective flap from returning to its protective position when you retract the key. A little gentle teasing with a small flat blade screwdriver should rectify this.
I Lubricate all the locks periodically, on the front locker, and the access doors to keep them in great condition.
Let us know how you get on ...
Edit: Are you sure the barrel has actually snapped ? - By design, if the key is inserted and the whole lock housing is rotated sufficiently, the barrel can be completely removed. This is normal and is no cause for concern. If you’ve now put the barrel back in, try lubricating and let us know how you get on.