imported post
I had a similar problem in Yorkshire last weekend and the solution was easy. Due to the fact that the panniers are slightly smaller and we tend to overpack them, the lock hinge tends to bend under the pressure when we close it. I closed mine until it was just slightly open and looked in with a mini maglight. I noted that the lock was not lining up correctly with the entry to the lock mechanism and if there is the slighest rub at all, it will open at the lock but the lock rubbingwill not allow the piston to openthe doorsmoothly. After a number of attempts it finally opened and I removed the lock pins on the door itself. I noted they had become slightly bend under the pressure of a slightly overpacked pannier, which prevented them from entering the lock correctly dead centre without rubbing. Using pliers I straightened them and replaced them. Result was the door is now opening smooth as silk again. It is imortant that the lock on the door is entering the actual locking mechanism smoothly dead centre and you can feel no rubbing as you close it into the lock, as this appears to be stopping it from opening smoothly. I would have a look and try adjusting the lock pins first as it solved my door that wouldn't open. For a bike costing over £17,000 the lock pins are a disgrace and with constant adjustment will weaken and more than likely eventually break. They are much to thin and weak, bending at the slightest pressure on them.
If this doesn't solve your problem then it is a new lock under warranty as the others so rightly indicate.
As a little footnote I have contacted my dealer and order the new part myself. What I did in Yorkshire should not have been neccessary and I thank other members including Steve Saunders for the info.Particularly the part number of the required item thatI was able to give my dealer who knew absolutely nothing about the problem.