I used to have TONS of problems with metallic threads.
What resolved 97% of my problems are listed below.
Of course I have only done a couple FMQ projects using
metallic thread, I DO however use metallic for machine
embroidery a lot.
90/14 LARGE eye SHARP needle.
Thread Net
slow the machine speed way down.
Also I mainly use Floriani metallic threads, so far it is the
only brand I found that works well for me without all the
troubles.