"I've had this exact same broom for 30 years, though I've replaced the handle 10 times, and the brush head 20 times."
If you live in her house, where she pays the electric, net, food, water, etc, and you don't pay much towards, then I'm afraid you've not got much of a leg to stand on. Yes its mostly yours but I suggest you save up and get the few remaining bits (case being the main one, so it looks different) and truely make it yours.
As others have said, if you can get old crappy stuff to slap in the old machine so it half works, and give her that, all the better.