I've had my Brother CS60001 for nearly 3 years. Made almost 100 denim quilts with it.
I took it apart to clean and look for "things that don't belong in there". It is making a clunking noise and bunching stitches unedrneath.
I changed:
1. needles (universal, ball point, heavy jeans needle-all new from the packages);
2. thread from Gutterman to Coats and Clarks (my usual thread)
Any other tricks I can try? Machine i useless but clean!