The grease and oil have frozen it. You can get it off. A blow dryer will get the metal hot. A rubber mallet with a few hits (protect the wheel with towels). Oil around it. Loosen the stop screw. It will come off. When you do get it off, clean the inside of the wheel (rubbing alcohol or degreaser- don't get any on the machine paint). Add a drop of oil. Before you put on the silver wheel, take off the hand wheel. Make sure you mark the placement of the washer between the silver wheel and the handwheel. It only goes on one way. With the handwheel off, clean the shaft, clean the gear out (wood toothpick), a drop of oil on the shaft- put it all back together. This will make sure when you wind the bobbin, the needle bar is disengaged. I have 4- 301s and have had to do this on 3 of them when I got them. You can do it.
Linda