Yo are using a piping foot to run a normal seam! You should not be surprised it will not work right. And admittedly I'm not used to imperial measurements, but I think the "bad foot" is further from a standard foot. It will not hold down the fabric evenly.
I'm quite sure that the problem lies in the hole of that presser foot. Just some deburring might not be enough. Polishing (also inside the hole) should do the trick.
Very very strange, since the only part that you have changed is the foot. I had my experiences when I was repairing sewing machines, and it doesn't take much to mess up the top tension. And that is the case here because it doesn't pull the bottom thread up.
