Matt-thanks for the tip,I'll give it a try.Unfortunately,I also have 2 bad knees-55yo- that are more comfortable with a 90 degree bend.
My hamstrings might pull a bit-one of the knees has an unrepaired torn ACL(since 1968), and I tend to emphasize leg curls over leg extensions in an attempt to stabilize it a little.I do both, but I probably save my best efforts for the curls.I do do leg presses, extensions along with the curls, but my best efforts are on the curls.
I will give the towel a try. In fact, I'm uncomfortable in the Prizm after about 2 minutes.
Thanks,
Charlie
PS-My wife-63-has no problem with it, but she teaches ballet, and is very flexible.