Hi @kayb,
A warm welcome to the Bunnings Workshop community, it is fantastic to have you join us.
Can I ask you to upload some photos of the mower?
Can I also ask what the model number of your mower is?
If you need a hand uploading images, please let me know.
It may be a simple case of flexing the casing slightly so the button will spring back into place, or there could be an issue with the mechanism which would entitle you to a replacement assuming it is still under warranty.
When we have the extra details that I've asked for above, I will happily assist further.
Jacob
