You said your mother doesn't speak English, but didn't say what country she lives in, and where she bought the machine and whether it was new. If your mother is not in North America, it could be a power problem, although Pfaff is a European brand, so it should work there, too. Check
www.pfaff.com . For most countries, there is an email address for Pfaff (but not for the US - where they search for dealers).