I finally figured out that I don't need a knee lift with my Pfaff 2170 - I just tap the foot and it goes up - another tap and it goes back down.
I also figured out how to put the needle down for paper piecing without the pressure foot going down, too. I 'fool' the pressure foot by starting to put the needle down; the foot goes down, but I haven't put the needly in the paper; then I raise the foot and REALLY put the needle down. If anyone knows a setting that eliminates the extra 2 steps, please clue me in!