There are certain things you might need to check before you decide that your sewing machine needs to be repaired and send it out to the mechanics. Knowing these tricks will most probably save you lots of money.
Do I need to oil?
It depends. If your machine is showing troubles in stitching, you might want to try to oil it, but using just a few drops. Lubrication is something that helps the whole system work smoothly but it will not work miracles and using too much oil might have the opposite result in your machine.
Threads play an important role on the maintenance of your sewing machine you can read some more information here http://www.sewingmachineexpert.com/. If you use good quality of threads, new one and avoid old threads, you will see that no waste of cotton will be accumulated in the inner parts of the machine, causing them dirt and eventually block them from working properly.
You should change your needles often, even if they are not yet broken or damaged. If your needles bent or break, they will create huge problems in your sewing machine. You may notice that unexpectedly your machine is not stitching smoothly; instead it is causing the thread to break. This is a signal that you should change the needle.
Make sure that you are using the proper size and type of needle and thread for your machine. If you use larger or smaller sized needles, it may cause the thread to break.
Also, do not forget that the flat side of the needle has to face away from where the bobbin is placed. If the bobbin is inserted from the front side, than the flat side of the needle has to be facing the backside of the sewing machine and vice versa.
How to adjust tension?
This is the most delicate process when it comes to sewing. It needs proper training and untrained people should not try to do it. Only professionals that have experience with adjusting the tension to the bobbin should do it. The only positive side is that once it is set up, it doesn’t loose the settings just by itself anymore.
The usual setting of the bobbin is nr 4 and when the sewing machines get out of the factory they are set to zero. There is an indicator showing numbers from 0 to 9 that helps you realize what is the current setting on your machine.
If you think you have problems exactly with this part of your machine. You may try to verify your doubts by using two different colored threads. This way you will be able to realize what is giving you the troubles.