I also have that same machine and I also noticed that there was some play on the 1/4" foot. I could wiggle the flat of the foot
I found below the snap on part there is a teeny screw. I got my smallest screwdriver and tightened that screw (its right above the flat part of the foot, right behind the needle when down). You have to raise the needle to see it and tighten the screw. This seemed to help take the wiggle out of the foot and helps my true 1/4 seam.
Try that-cheaper than a new foot-too late for that tho-one can always have a spare.
Good luck
Jill M