If your Bernina 790 or 790+ sounds like mine did, it likely has a defective hook.
I now LOVE my 790+ but it wasn’t without it’s share of issues straight out of the box.
First step is to properly oil the hook. This will initially quiet it down significantly, but if it starts getting obnoxiously loud and rattly shortly after oiling it, you may have a defective hook. In addition to oiling the race (as described in the manual), add a little oil to the flat surface around the edge of the hook, and also a few drops to the two felt pads on the inside of the hook.
If you’re still having problem please contact me and send me a short video of your noisy hook :
- Unthread and remove the needle.
- Lower the feed-dogs and place a piece of fabric under the presser foot.
- In Sewing settings, shut off the bobbin and upper thread sensors
- Open the bobbin compartment door (but not the metal latch that hold the hook in place). Leave the bobbin case installed.
- Record a video and run the machine at various speeds.