The machines needs cleaning, lubricating and the timing redone. Take it in for service. Normally needs doing every couple of years if you use it frequently.
'bird nesting' is caused by incorrect tension. Start with adjusting the bobbin tension and then the upper thread tension. It is a delicate tugging match, to put the loop in the centre of the two pieces of material
https://www.google.com/search?q=sewing+machine+tension
..
Did you get a slant shank even feed foot? The Singer 4622 uses a slant shank. Sewing machines can have a high, low or slant shank foot. I would expect the wrong shank walking foot either being too high or too short from the shank screw to the needle plate on the Singer 4622. The appropriate presser feet are shown here: https://www.sewingmachinesplus.com/singer-4622-parts-accessories.php .
I hope this helps. Otherwise, check if the presser foot lifter is working properly to lower the foot.
Cindy Wells
Does the motor rev when the foot control is pressed down? If you don't hear the motor, then the problem could be the foot pedal rheostat or the motor itself. If you do hear the motor, then the motor belt is probably worn. The belt connects the motor to the hand wheel to needle bar mechanism.
The parts are available from several suppliers, including https://www.sewingpartsonline.com/singer-2000-sewing-machine-parts.aspx?index=72 and https://www.singeronline.com/2000.html . These sites have both the motor belt and the foot control.
I hope this helps.
Cindy Wells
You can't--something is stopping the wheel from turning, and until you find out what is stopping it, your machine will be locked up. Take a look below the bobbin case, and you'll see a ***** holding a little door. It allows you to clean and see on the other side of the bobbin basket. Chances are, there's something like a broken off needle stopping the gear that turns the hook. It can also be caused by threads wrapped around the tension disks, or around the inside of the hand wheel itself. The hand wheel can be removed by removing the cap in the center--it is hiding a ***** that holds the wheel.
Hi,
On some of the singer touch an sew machines the feed dog has little rubber pads instead of metal teeth.
With age the pads come off.
A replacement feed dog can be had from SewingPartsOnLine.com for about ten dollars. http://sewingpartsonline.com/
I hope this helps, I have changed quite a few.
Bob
This is sometime caused by you using a new or different brand of thread that has a weaker tensile strength, (Snaps with less force), or the tension on the spool might need adjusting.
If you supply the model number there is a good chance I can.All Singer sewing machine serial numbers start with at least one letter and is embossed on the machine, not the pedal unit.