Dual spindle uPVC gearbox

[phillpark]

My French doors have stopped working. I can pull the handle up or down but it isn't engaging the multipoint locks.

There is one spindle in the door, but two spindle holes. Should there be a spindle in each? My lad said he tried to open the door, heard a clang as if something has dropped inside the door, and now it doesn't work. But I can't see how a spindle could have fallen out and disappeared?

If the door isn't activating the multipoint locks (I've tested them by hand and they do move as expected) does that mean the gearbox is knackered?

And if so, how do I know which replacement to buy?

 

[ronniecabers]

Sounds like the gearbox to me. The second spindle hole will be for a 'split spindle'and only fitted in certain circumstances.
The only positive way to know which gearbox it is is to remove the door lock and compare what is available. You should have manufacturer name stamped on the faceplate , such as GU/Ferco/safeware/yale/Winkhaus , there are others too. You will need the backset ( distance from faceplate to centre of spindle hole ) , and the PZ ( distance from centre of spindle to centre of the round bit of the door lock barrel. They are the bear minimums! The reason it is worth removing the lock is to check you are getting the right one, somebhave variations that look very close to others in the same range.