If the "stop motion" knob located in the center of the hand wheel is loosened the entire Featherweight sewing machine should not keep running when you wind a bobbin, just the hand wheel. We have "stopped the motion". Should have at least. If not the cure is to remove the hand wheel and clean the hole (bore) of the hand wheel, oil it well and reassemble the hand wheel. This only takes about ten minutes. We begins by removing the hand wheel.
Get a washcloth and fold it twice, into quarters. lay it on your base extension and lift the extension all the way up as if putting the machine back into machine's case and then tilt the machine forward until the machine is resting on the folded up base extension and the hand wheel pointing to the ceiling.
Toward the edge of the stop motion wheel (knob) is a small screw. Loosen it by three full turns and the stop motion wheel can be unscrewed completely (lefty loosey, righty tighty). There is an odd washer that can be seen now that the knob is out of the way. It fits on the exposed end of the shaft that the hand wheel spins on. The washer has three tabs spaced evenly around its outside edge and two bent tabs on the inside of the washer's hole that fit the slot in the end of the shaft.
Leave the washer on the shaft until you get a felt tipped pen or something you can scratch steel with. We need to make a mark from one side of the hole in the shaft out across one side of the washer. The washer we are speaking of has to go back onto the shaft the same way it came off of the shaft. When you put it back on make sure the mark is up and we will know the correct side of the washer is up and align the marks across the end of the shaft and the side of the washer and we will know the washer is "clocked" properly as well. Felt tipped pens work well but the mark will go away after awhile. I prefer something that will mark (scratch)the steel of the washer for keeps.
Remove the washer and pull up on the hand wheel. Notice: I did not tell you to remove the motor belt. The hand wheel will pull off the end of the shaft with the belt left on and you will not have to adjust the motor drive belt's tension if you don't have to loosen the motor and remove the belt. Get hold of the hand wheel and pull. If it just moves a little, slap it back down and pull up smartly again. Repeat if necessary. It will really will come off.
Ultimately we are about cleaning the hole (bore) through the center of the hand wheel and oiling it well. Oh, and putting it all back together.'
There are two simple ways to clean the bore of the hand wheel. Steel wool or fine sand paper. With four ought (0000) steel wool I pull off a one inch ball of the steel wool and pull it thinner and larger, pulling at the edges, without tearing the little pad. Ladies, I suggest you put on a rubber glove on your "using hand" and everybody cap the end of a correct sized finger needed so you can push the pad into the bore of the hand wheel and twist your finger like you do with the wash cloth in your ears on Saturday night bath-time. Don't dab at it, honestly clean the hole out. Change sides of the hand wheel and work from the other side as well. The bore of the hand wheel is one of the most neglected places on our machines and it frequently is dry of oil and it cruds-up preventing the hand wheel from turning freely.
The other approach is to roll a piece of wet and dry sandpaper about two inches wide and six long into a tube rolled around a finger that allows the sandpapered wrapped finger fit the bore. 220 wet and dry sandpaper (used wet) works well.
Either way you do this you will end up with a dirty finger and that shows we are cleaning crud out of the hole. Keep working until you are not finding any more crud to get your finger dirty with.
Clean the bore of dust and such caused by your efforts and put some oil in the hole/bore. Put a little oil on the exposed end of the shaft and put the hand wheel on the shaft without the motor belt and give it a spin by hand. The hand wheel should turn very freely. If that is the case remove the hand wheel again and loop the motor belt around it and put the hand wheel back onto the shaft. Install the washer with the mark up and aligned with the mark on the shaft and install the stop motion knob. Turn the little screw in that is out there on the edge of the stop motion knob. Not tight, just there.
It might take a second for your machine to buy into the idea its clean again. Loosen the stop motion knob and run the machine electrically. Give the machine a little while to break-in again. If the machine is thinking about not turning with the stop motion knob loose, run the machine and hold the thread take-up lever to stop the machine yet let just the hand wheel spin for a bit.
Source: Dave's Blog