The top thread on my Frister and Rossmann Fantasy 972 loops no matter what I do. Adjusted the top and bottom threads makes no difference. I noticed the top thread catches between the bobbin case and a nearby metal component, making a loud clicking sound which is probably caused by the bobbin case being the bobbin case being pulled out of its housing before the thread frees itself.
Go right the way back to the manual and check you are threading correctly. I've been caught out by the thread not being properly looped over the tension lifter arm.