It needs lubrication and probably some cleaning. Your instructions tell you to only oil the bobbin case because you're expected to take it to the shop for an annual service where it would be lubricated. On this era of Pfaffs, I believe they used a white (likely lithium) grease which can dry out over time. Some people have reported having to chisel off the dried grease in machines that have sat for a long time. You might want to find the service manual for your machine (I believe it's available in a few different groups--try Yahoo's group Pfaff_fixit or the Facebook group "Vintage Sewing Machines" in the Files of either group). That manual will be helpful on how to disassemble and reassemble. I found the handwheel a little tricky to get back on until I found the manual in order to get the spring installed. Also be aware that the screw that holds on the handwheel is plastic and breaks easily (although you can get replacements, save yourself the $7 and don't over tighten). Clean, oil and lubricate and I'll bet the problem disappears. Good luck.