it`s a fault with your locking mechanism (lock-strip).
the central gear-box is the part that usually fails.
when you took the handles off and looked inside, that is the central gear-box. above and below the gear-box are two sliding strips (bars) which operate the locks. these are detachable from the gear-box.
there are many different lock-strips therefore many different gear-boxes.
a new gear-box ranges anywhere between £50-£100 on the internet.
getting the right gear-box is essential.
replacing a gear-box should really be done by a competant person who is familliar with upvc locking mechanisms.
is money tight and is there anyone who can help you?
levilewy
April 2010