I myself have serviced one of these machines. No it cannot handle hemming jeans. It very light and full of plastic. It easily rips out of time, meaning it will start skipping stitches or not make stitches at all. These are cheap frustrating throw away machines. Their ability to last over time is a game of luck. Every part they have in them is screwed into plastic, meaning the ability to service the machine is non existent, well honestly service. I have a few suggestions for a sturdy affordable machine. The Elna sew green is a simple strong machine with a full iron casting. For christmas you can easily find these for $199. I know it more than the costco one but the extra $50 is well worth it
http://www.elna.com/en-gw/model_sewing_sew-green.php
I also recommend the full size hello kitty. Unlike most kids machines this one is not a toy. Its a full size machine with a full metal casting. this listing has it at $189 which is a great deal.
http://www.hayneedle.com/product/jan...FU8XHwodXdQEgQ
You can still find new machines built as well as the old vintage ones. I have nothing against the vintage ones but when it comes to kids, she will have more parts, feet and options available to her with a current machine.