Old fashioned machines worked well with almost any thread. Newer ones are faster, with more parts & don't need to be oiled. Low-quality thread (which may include some that you formerly thought of as good) will shed lots of lint. Lint is the enemy! Lint clogs the tensions...accumulates under the bobbin case...and generally makes most machines very unhappy. Changing to a premium-quality thread (& the right needle) will solve many an issue. Even the most expensive thread is cheap when compared to sewing machine repairs. good luck