My right one always had a tendency to catch on. Never took the time to take it apart though. The behavior of the lock hardly changed since I bought it.The bike was new as I mentioned (0 miles) and on the day of delivery the dealer was in the process of handing over the GT to me when during the demonstration of the pannier operation, I could not unlock one of them. At this point we agreed it could be fixed at the first service. Subsequently after I had ridden the bike home it became apparent that to resolve the problem the dealer would have to replace all four locks and replace the panniers. At this stage I explained that to replace all the locks would mean substantial 'repairs' that I would not accept on a new bike (I would not accept a warranty fix as the fault occurred in the showroom).
Both MCS and Triumph have shown exemplary customer focus in dealing with this issue. I have owned Hinckley Triumphs since 1993 and I am not really surprised at this behaviour. It has not cost Triumph very much much (they have another demo bike on their books which can be sold with only a few miles on it). They have gained much in future sales from me and anyone else who hears about this (and other) incident. I wish many other companies would behave like this!