A lot of people swear by CT, but my friend had nothing but problems with it breaking on her Viking. I would switch thread.

I was trying to use up thread because I started to use nothing but Kig Tut and Masterpiece. I had so much breaking. I was so frustrated. Change the thread.

I have had good luck with a metallic (metallica) needle. this needle has a hole designed so that it will not shread metallic thread. Worked well when I was FMQing. I use Connecting threads in all my Vikings & Tin Lizzie. Having said that, you can always get a bad spool and some machines are fussier than others. It pays to try different threads!