My Juki came with a 1/4" foot. My machine also unthreads itself when I use the thread cutter and some threads are worse for this than others. I find any thread that is the least bit stretchy just springs back when the thread cutter is used. My 100% polyester thread seems to be worse for this than my thread that has some cotton in it. Loosening tension and using only the one hole of the thread guide at the top has also helped some. This is the only complaint that I have with this machine other than I don't know how to use the automatic needle threader although I have read the directions and tried to follow the pictures in the manual countless times without success.