I using elna 8300. suddenly it take noise but i'm not sure, is that from under the bobbin or near belt. when the noise come the belt is shaking hard. and the result is not good.
i have oil as instruct from manual book. it heard when slow run.

rahmat, April 2011

Your problem is very common & due to lack of servicing.If you remove the plastic bobbin cover & the bobbin & look into the bobbin case you will see a small hole in the metal bobbin case base.Apply a few drops of sewing machine oil into the hole & by hand turn the machine in REVERSE,6 turns should do the trick.Run the machine with no thread at high speed for a few minutes to allow the oil to work it's way in.It is vital for the machine that you oil this spot on a weekly basis.

Sewman, May 2011

You need to check to make sure the motor has not come loose first of all then take out the bobbin case completely and check to make sure there is no thread stuck there.

ken, April 2011