Necchi sn service

Safety first: Unplug the machine from the wall outlet.

Refer to Figure 1 for number identification.

Figure 1.0 1. Turn your cam/design graduation knob (14) to 4.

2. Turn stitch length regulating knob (24) to 4.

3. Open automatic mechanism lid (13) on top of the machine.

4. Remove screw in left front corner to remove the cover of the machine. (See Fig. 2)

5. It is a good idea to mark settings before you remove the cam mechanism. There is an adjustable coupling on the front of the mechanism. It is a long nut with a small nut butted up against it to keep if from turning. It regulates the forward, backward and stitch length settings for the cams. (See Figure 3.0)

Figure 3.0 Clean the edge of the screw threads with the alcohol to remove oil. Let it dry. Then using fingernail polish mark the position of the screw threads and coupling. It is very easy to turn this part of the mechanism and it can cause the cams not to sew out as they should. (See Fig 4)

Figure 4.0 6. There are 4 screws that hold the cam mechanism in the machine. Pull the automatic disc stop motion lever away from the machine and remove the back right screw first. (See Fig 4) 7. Release the automatic disc stop motion lever back to it original position against the machine housing.

8. Remove the other 3 screws from the housing.

9. Carefully push the reverse button (23) in as far as it will go. There is a U-bar attached to the mechanism on the right front side that works the reverse motion for the cam. (See Figure 5.0) You will have to lift the mechanism up and flip it to the right. This will let the u-bar go down far enough to remove it from the reverse lever.

Figure 5.0 10. You should now have the cam mechanism out of the machine.

It is best to be working on a flat surface to catch small parts when working on this type of mechanism. On the bottom of the device there are two springs attached. The long spring (See Figure 6.0) is used to keep tension on the came mechanism housing. Remove this spring first.

The second spring is smaller and under the long spring you just removed.

It is connected to black piece of metal. This is the adjustment for fine tuning the number of revolutions set by the cam retention spring.

Carefully remove the spring and set is aside. See Figure 6.0)

Figure 6.0 11. There is a black piece of metal with two screws on the side of the cam mechanism that has a piece of metal wire under it. This is holding the tension spring for the cam spindle. Mark its position with fingernail polish and then remove the two screws. NOTE: Mark if the spring wire is under the piece of metal or if it protrudes from the side. This will also affect the number of resolutions since it affects the spring tension.

12.

On top of the cam spindle is an E-Clip.

(See Figure 7.0.)

Figure 7.0 13. Use a small screw driver and remove the clip. There should be a small thin washer under the clip. You should now be able to remove the spindle. Push down on the top of the spindle and remove it from the cam mechanism housing. Carefully note the position of the springs and inner parts.

14.

There is a metal V spring in side the spindle cup along with two metal pieces on each side. You will find a small slot on each of the two metal pieces. This is where your pin on top of the mechanism is supose to be positioned. When the pin holds one side of the metal piece it pushes against the inner v spring.

As the outer mechanism is moved and releases the tension on the spindle spring the cam will rotate. It is much like a ratchet mechanism.

My inner cup was full of old oil that had gunked up and froze the movement. I used automotive degreaser to clean it out.

WD40/kerosene will also break down the old oil. You will need to clean all the pieces of the spindle mechanism. Reassembly is not as easy of reversing the steps.

After you put the two metal pieces back in the inner cup and install the v-spring, you will have to pull each turn of the outer spring back down around the spindle housing. Your basically opening up the spring to get back around the spindle housing. They you can start your reassembly. The pin can be confusing. I removed it and reassemble the cam mechanism. Then turned the spindle with a crescent wrench and looked for the small slot and pushed the pin back down from the top.

There are three things to watch when putting the mechanism back into the housing. There is the needle position lever that is on the back of the mechanism, the zig-zag position lever which is on the front and the dreaded U lever with controls your forward and back movement.

The U lever is not difficult, but make sure you get the needle position and zig-zag lever back in place. If your having a lot of difficulty seating the mechanism, you can turn the hand wheel it will move the wobble gear and give you more room to push the mechanism down. You my just have to work with if for a while.

Hope this helps.