Fred wrote:
Hello,

The hinge on our window buckled when pulled a bit too hard. I don't
think it helped that the runners had not been oiled for a while.
Should I use 3 in1 or WD40 for this in the future?

A light smear of 3 in 1

I see that there are two types of friction hinge: a 13mm and a 17mm.
What is this: their depth? Across which point do I measure this?

It's the width across if my memory serves me right.

I bought a pair but I notice the holes do not line up with the ones in
the original. Is this a problem? What is behind the uPVC? Is it a
wooden frame? If so, could I just put the screw where the new holes
are?

Just insert the screws into the frame using the holes in the new hinges -
different makes have different locations. Just remember not to overtighten
the screws as the 'thread' will easily strip in the uPVC.

AND buy the 'proper' screws for the job from the hinge supplier.

TIP: if the thread has stripped in UPVC - and providing it's the original
screw, it's possible to buy slightly fatter 'repair' screws to overcome this
problem. (Possibly teaching granny to suck eggs here though)?

Generally nothing in the uPVC - unless the window or sash is of such a size
that it needs reinforcement - and that will usually be either steel or
aluminium.

Or are these holes in key positions and should I drill a hole in the
hinge to align with the existing hole?

No - see reply above.

Thank you for your help in advance.