Everything worked just fine except the fact that if was jamming from time to time. So I open the upper lid, take a look inside and notice 2 plastic gear wheels, one cam-gear and one from a top vertical shaft. They were made from PLASTIC and cracked. So every time the crack was coming in contact with reciprocating wheel, the motor could not turn over, the gear being out of sync.
Well I told myself it would be quite a project to fix it and so I looked up on e-bay for new components.
Of course, I count find a technical manual for it, so before I take it apart I had to study it, understand how it works, so I am able to mount it back in the end and calibrate it, since everything will be out of sync.
The ones from the bottom that connect to the shaft had to be removed also.
As they were a lot of joints and the oil on them was very old, I also took this chance to oil all the joints with some ultra fine oil, for fine mechanisms.
All I have to do now is to calibrate the bobbin case movement in relation with the needle movement because as it is now, after it´s done, it seems that the needle hits the bobbing case, but that´s easy.
My question is: why did they choose the most important parts and the ones that also take the most load to be made of plastic, especially that type