Brother SE 270D Cassette threader

When you push the cassette down, there is a little tiny wire hook that comes through the needle eye to catch the thread. The needle must be in perfect alignment for the wire hook to go through the eye of that needle. If the hook is bent a little OR the needle is bent a little or not all the way up, the needle won't get threaded. The wire will not go through an eye smaller than an 11/90. First thing I try is a new needle that is all the way up in the needle holder. If threading still fails, probably the wire hook is sliding to one side of the needle, not through the eye. The action happens so fast, it is hard to see exactly what the problem is.
Hope that helps. I am not a fan of the cassette system. A side arm needle threader is easier to problem shoot.

I encountered the same problem when I first started using my 270D. When you push the cassette in, do so very slowly and smoothly...it takes some practice. Now my needle threads 99% of the time. Also make sure tension is correct and the thread it not too tight in the cassette. Hope this helps.

I had a hard time too. I have found that you can see the needle threader through the 'window' and you can see when the cassette engages this part of the mechanism to take the thread down to the needle. It is to the right side, so you need to make sure the cassette is pushing on this on the right side. Hope this helps.

I too have a christmas gift causing headaches - loopy embroidery. But at least this one I found a work around for... I thread the cassette according to the arrows but when I get to "6" I loop up around the left side and over the top of the bend but DON'T go far enough to cut the thread. I leave about 4 or 5 inches loose and hold the end at the top-right of the thread cassette at about the 2 o'clock position. I push the cassette down into the machine normally and right about when the 6 is below the window the thread will cut leaving you holding the left over piece. Continue pushing down until click and needle will thread. Have not had any threading problems since learning to leave a tail on the thread. Hope this helps.