Necchi saemaster is frozen will not go up or down

It is likely that you need to open up the bobbin area and remove the parts to clean out all debris. The feed dogs should also be thoroughly cleaned. Try to remove the needle prior to doing this. When you have removed all of the parts from the bobbin area you will notice the hand wheel can now be rotated. Check all of this and make sure that the race is oiled with one drop of sewing machine oil. (small area that the bobbin case sits on - lower and looks like a car race area) Go ahead and blow out everything with canned air. Oil all moving areas with oil while it is open.