You may need to change hinges if:
- PVC window does not open or close smoothly
- There is a certain gap on the hinge side, when the window is closed
- Some part is visibly broken.
You may need to buy new hinges, and you need to know next:
- Type of hinges (top hung / side hung window)
- Length of the hinge
- The stack height of the hinge when closed.
You may buy new hinges at a local shop telling them what type of window you got, they will offer you the ones you need. You may also buy cheap hinges on eBay, provided you know the length and the stack height of your hinges.
When replacing the hinges, you will need to replace both of them:
- Open the window and unscrew your hinges from the window frame
- Lift the sash out
- Unscrew the hinge from the sash and put the new one on in the same position
- Turn the sash around and change the hinge on the other side
- Put the sash back into the frame and screw the new hinges onto the window frame.