Oh, it's exciting to read of your love for your 301s. I tested the knob to adjust the feed dogs and that seems frozen so we'll have to try to release that. My hubby recently restored a Kenmore that had frozen up near the pulley and our friend used a gear puller to loosen up. Hopefully, we'll have the same success with the feed dog knob. My sewing ministry at our church was given six vintage machines today by a very generous person. Three of the machines are in the bentwood cases. Two have not even been opened because the keys are missing. The third has a spindle bobbin. Two machines are in cabinets and I think one is the two tone 301. The second one in the cabinet is a green Necchi. We have a lot more to discover about these beautiful machines. Does the 301 have a serial number?