I was looking for something else and happened to see
this old thread. << link I didn't realize that the MTx190 is a round shank. It will work, but it one needs to install it so the grove is the same way that the flat shank does. I used to think how difficult it would be to use a round shank needle and get it lined up correctly. I have a machine that takes round needles, so I had to figure it out. I used a needle threader in the eye with the groove on the correct side and found out that it was easier than I thought it would be.
Janey - Neat people never make the exciting discoveries I do.