Joe, that machine does not have the embroidery unit installed, so is a ss/zz only. It could be the stopmatic, but it could also be a $50-$75 internal belt. Or another issue. If it were a CL machine, it would be well worth the effort and time to see what's wrong with it. I would consider such a machine a gamble buying it via GW and wouldn't pay more than I would for a parts machine. And keep in mind Pfaffs usually go somewhat high (non-working) simply for the parts. And I sure wouldn't pay to ship a parts machine that weighs 45 lbs. It's a nice looking machine though, but I bet it sells for at least $50-$75....or more. Those dang belts!
I should also add, that they are prone to having locked up dials (stitch width) etc. and can also be prone to being stuck into a zigzag or slight zigzag. I've purchased 4 vintage Pfaffs and 3 of them had needed intense rehab. and a lot of cash thrown at them. I love them and they were worth the time and effort but that's something to think about.