Door multi point locking system

[paldiy]

I have a problem locking this door.The multi point latches appear to be working ok but when I come to lock it the key turns half way and then meets resistance. The handle has to be turned up as hard as possible and the key will then complete its turn with difficulty. The same happens when unlocking. This problem also occurs if I attempt to lock it when the door is open so it cant be caused by the keeps not being in alignment.
Ive also tried a different eurocylinder and there is no improvement.
Help please.

 

[HERTS P&D]

Your door has dropped, open the door and see if you can lift it off the hinges. You will need to 'raise' the hinges.

I know as this happened to my door.
I removed the door and placed 2/3 fibre washer onto the hinge and replaced the pin which made the door sit higher and lock as it should.

Andy

 

[Alarm]

Not necessarily, mark off the locking bolts, lugs and see where they meet with the retainers/keeps.
There may be adjustment there or on the hinge`s.
Lifting the door and packing out may well make matters worse and is a last resort.

What is the door made of uPVC or wood?

 

[JohnD]

but he says:

This problem also occurs if I attempt to lock it when the door is open so it cant be caused by the keeps not being in alignment.

 

[Alarm]

Sorry missed that.
Was put off by the "remove door" post.

OP remove the cylinder and turn it around and test.
If that works ( I know one side you may not be able to use the key this is a test) you need a new cylinder, if not the lock is worn and needs replacing.