Can't remember the name of the main supplier of spares for Chinese tat tools. Do a quick G##gle search for "power devil spares" - that should find them.
That said, you're unlikely to get any significant spared support for buy 'em cheap and pile 'em high store branded Chinese tat. That's one reason it's cheap - minimal support.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix lawn mowers.