I have had Pfaff sewing machines for nearly 40 years and I own a Pfaff 1222. Yes, it's a great machine. I hate to say this but I think the sewing repairman could be ripping your family off by possibly charging up to $1,000. He's feeling the waters to see if your Mother and Grandmother will pay that much for a repair. They need to put a limit on what they will spend or he will pad the bill up to near a thousand. He will most likely repair it for 500 or $600 max. regardless of what is wrong with the machine.
Also, some Pfaff parts are no longer available from Pfaff, though ebay frequently has used parts that are frequently used to replace broken parts. My point is that even though the machine may be repaired today, it can break a plastic cam in the future. YOu would still be able to use the straight stitching but I'm not certain about zig zag. The cams are
for the other stitches.
I'm very sentimental about family also, but sewing machines are sentimental because of the person who owned it and not the machine itself. Hope you will not take this the hard way, but I've had experience with the sell and repair aspect of sewing machines and felt I should post this.