Necchi sewing machine problem

The is usually an adjustment to tighten the belts by moving the motor. There are other ideas here, clutch, the knob in the handwheel or the screw in the needle bar..

https://www.google.com/search?q=Have+a+Necchi+534FB.+The+hand+wheel+does+not+turn+the+needle+bar%2C+belts+are+loose

..

If it is an older mechanical machine, you are probably correct. It has probably seized due to lack of regular oiling and cleaning.


Wheel on right side that controls the needle up and down is very tight...

Suspect the machine is seizing due to lack of regular cleaning and oiling.


Wheel on right side that controls the needle up and down is very tight...

Perhaps it needs a good cleaning and oiling if it hasn't been done for a while.

Wheel on right side that controls the needle up and down is very tight...

It was working now it seems to be frozen the needle part wont move

...

There is a lever for positioning the needle bar. When you move the lever to the left middle or right , the needle bar too should follow the same. Try to do that. If it doesn't follow the lever and stays at one end, that means the machine needs to be oiled. Not like most sewing machines Supernova swings the bottom rod too to left and right when Zig Zag is engaged. I recommend to spray some WD 40 first, to inside of top and bottom side of the machine , and later to apply machine oil to every moving joints.

There are a number of things that could cause this.
Needle installed with flat in the wrong direction.
Excessive thread tension,top or bottom.
Lack of lubrication. If the machine can do anything more than a straight stitch the mechanism can gum up and not move the needle correctly.
Here is a link to threading directions.
Necchi 3537 Sewing Machine Threading Diagram

Most sewing machines can use a double needle, the one with the single mounting shank and it turns into two needles.
MAKE sure you have Zig Zag needle plate installed to accomodate the double needle.
Turn hand wheel slowly to test then use thread and fabric and turn flywheel by hand to test sew.

I have just fixed a similar problem took about 30 seconds the customer had left the bobbin winder engaged

sounds like the feed dogs may be down or not working. Watch to see if the little teeth are moving under the pressure foot when you stitch( try to run unthreaded and with foot up no fabricto check) May be a button to turn up the feed dogs.

I solved this problem for a friend,!. the needle was in the wrong way and
2 the bobbin case was not properly seated be sure you hear the 'click 'when
reinserting the bobbin case...hope this is helpful Velz