I have to adjust on my Janome 6600 as well. Center position is 3.5, I use 4.2 with my 1/4 foot to get a good scant 1/4 inch. I discovered that I could reprogram the machine's needle settings so now 4.2 is the default setting when I turn my machine on. I just have to remember to move it back to 3.5 when I want to center my needle (which I have programmed in to a second button!)