Hi @ddv1,
Welcome to the Bunnings Workshop community, it is fantastic to have you with us.
Let me ask a few questions so we can try to narrow down what is causing the issue.
When the door is open, does turning the handle make the latch bolt move fully in and out?
Does it feel like the latch bolt is reaching full extension?
Does the latch bolt seem to line up well with the hole in the striker plate?
How deep is the hole behind the striker plate?
I am trying to ascertain whether the issue is with the latching mechanism itself or the location of the striker plate. If you can answer these questions, this would certainly help.
If the issue is with the lock, I'd suggest uninstalling it, applying some silicone lubricant down the latching mechanism and then reinstalling it. This might help to realign things a bit better.
If the issue is with the striker plate, then unscrewing it, deepening the hole behind it with a chisel and ensuring the striker plate lines up perfectly with the latch bolt would be the way to go.
If these two things don't work, then you may need to replace the door handle, as something in the mechanism might have failed.
Let me know what you think.
Jacob
