I don't know if this could help but...... I hit a pin while sewing with my 301. I broke the pin into many pieces so changed it. After changing it, I had same problem as you- handwheel totally frozen. I took the entire bobbin assembly off so there was nothing on that shaft. I never found a thread. One day, i took another 301 out, put them side by side and compared them while turning handwheel on the one that worked. I found that I must have moved the needle bar up when I hit the pin. I would imagine thAt you could dislodge it with bad thread nest as well. The adjustment screw is on the upper side of bar, open the side door thing to access it. Loosen The screw and move the needle down and try the handwheel again.i just measured how much of the top of the needle bar sticks up above thee metal piece by the screw and it is exactly between the 1/8 and 1/4 mark on my ruler.i hope this helps you. These machines are very sturdy. You will be very comfortable doing these things after you fix this issue. Sometimes, I find that if I rock the handwheel just a little, I can expose those tiny threads that get stuck so I don't have to take the bobbin thing apart. Try to get in the habit of holding your threads and having the needle bar in the "up" position, this will minimize these issues.