I have rescued a 301 from the trash and have it working fairly well except I cannot turn the inner knob on the wheel to free the needle bar from going up and down when a bobbin is wound. However, I don't even know if the bobbin winder works because I can't get the knob to loosen. Any ideas would be helpful
I've had to resort to wrapping a set of water pump pliers in cloth and using that to turn the inner knobs on two of the machines we've bought. They were just so tight you could not turn them by hand. Nothing binding them, no rust, no crud, they had just been cranked down too tight. One of them actually has plier tracks on it.
Oil it first of course then if that don't work wrap a set of water pump pliers with rags and get a grip on it.
If you can't get the knob to move, you could just wind the bobbin with the needle arm going up and down. Not an ideal situation but at least you could see if it worked. On my old Singer treadle, I filled a couple of bobbins that way before I realized you could loosen the knob. I removed the bobbin case and took off the foot and needle and filled a couple of bobbins.