you can buy stuff that makes your needle "slicker" when sewing things like this. I would probably clean the bobbin & needle area with some alcohol after so many intervals of time.
use a Q-tip, gently. I know Bernina carries it, but can' for the life of me think of the name of it. there is also a pad (Bernina store) that you can just sew thru every so often that cleans the needle.