Lockwood optimum are the worst. They just break. And they are a sealed case so not even a clever locksmith like me can fix them. Also, I haven’t found an alternative product that’s a straight swap for these locks, so I have to keep buying them! Yay lockshop. Boo assa abbloy

LOCKWOOD OPTIMUM SLIDING DOOR MORTICE LOCK

There is a design problem with the internal locking mechanism in some cases where it will refuse or be very difficult to lock. Removal of the unit and turning horizontal allow the lock to function again - BUT only when horizontal. There must be a spring or latch internally that is affected by gravity. My experience is 1 of 3 locks has failed. Opening the main housing is not an option but there must be a simple fix for this ...

Good solid lock. Easy to replace. Unfortunately the old locks of this type seem to have failed and the key couldn't open the latch unless at a certain angle.

The online shopping experience with them was good, delivery was done by AusPost on time and everything was fine