I have some machines that INSIST on the correct thread weight and type for the eye size and size of the needle. Check the actual eye of the needle it may have a burr, you can also check to make sure you do not have two different kinds of thread..one of my JUKI'S hates that and throws a real temper tantrum.
SO many little things can go wrong it just takes a slow process of elimination. Let us know if you figure it out, it will help others.
Hope you figure it out soon.