Why machine sewing run so slow - Sewing Machines

If your sewing machine is slowing down during sewing and then goes back to normal, there are a few possible causes to consider:

1. Tension Issues: If the tension on the thread is too tight or too loose, it can cause the machine to slow down or even stop. Make sure the thread is properly threaded through the machine, and adjust the tension as needed.
2. Jammed or Dirty Bobbin: If the bobbin is jammed or dirty, it can cause the machine to slow down or stop. Remove the bobbin and clean any debris or lint that may have accumulated, and make sure the bobbin is properly inserted.
3. Dull or Damaged Needle: A dull or damaged needle can cause the machine to slow down or skip stitches. Replace the needle with a new one and make sure it's the correct size and type for the fabric you're sewing.
4. Motor Issues: If the motor is failing or overheating, it can cause the machine to slow down or stop. Check the motor and make sure it's properly lubricated and functioning correctly.
5. Machine Maintenance: Regular cleaning and maintenance are important to keep your sewing machine running smoothly. Clean the machine and oil it according to the manufacturer's instructions to keep it running at peak performance.

If none of these solutions solve the problem, it may be best to have the machine inspected by a professional to diagnose and repair any more serious issues.

try this link might help you out.
How to troubleshoot slow running singer sewing machine eHow UK .
or this link.
sewing machine running slow Google Search

Did you open the top of the machine and oil every place where metal rubs against metal? Did you do the same under the machine? Use only GOOD quality sewing machine oil. If the machine is slow to recover (it may take a while for the oil to sink in), you can direct hot air from a handheld hairdryer into the internal mechanics. AVOID trying to run the machine until it moves freely or possibly risk damaging the motor.

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tighten the belt

check the plug in to the outlet first
then check the power cord connection to the sewing machine
could be something wrong with the power cord
could also be something wrong with the motor
also could be a wiring problem

If the machine did sew fast the the replacement motor, then the problem might be that the machine is getting gummed up somewhere. Pull off the top cover, remove the 5 screws from the bottom of the base plate, (4 large screws, 1 small screw), remove the base plate remove the 1 screw from the bottom of the free arm cover. Now you can see most of the moving parts. Spray a little WD 40 on all the areas that you see metal to metal rubbing together, both on the bottom side of the machine and the top side. Don't flood the machine and stay away from the motor area. Plug the machine in, lay it on it's back and run it full speed, or at least till it runs full speed. After you free it up, blow out the machine with compressed air, and reoil with tri flow all the areas again. Run the machine again, and you've started your own tail gate repair shop.

If the machine turns easlily by hand then the problem is probably the foot control. If it is hard to turn it may need to be lubricated.

There is no speed adjust, but 1st you must know the source of the slow down. Remove the belt from the motor pulley and run it, if it goes fast try turning the hand wheel if it is stiff the machine needs clean and oil. If it turns freely you motor may be dirty or just slow. If dirty, sometimes you can without the blet attached run it at full speed for 10 to 15 minutes. It should get faster as you run it. If not motor is weak or slow needs replace. Just replacement motor as genuine probably no longer available.

Set machine to wind the bobbin to check for how fast the machine will run. I believe it will run fast or slow according to how hard you depress the foot control. If it runs fast and slow you have a problem in the machine. Most likely the machine, if turned by hand, is hard to turn and it needs to be professionally serviced. before it is ruined.
sewman7