Upgraded 10 turn potentiometers don't work whereas the original 1 turn potentiometers do. Why?
I'll make a WAG on this- the wiper is typically the rear terminal in 10-turn helical pots (vs the middle terminal on single-turn pots), so if you wired the middle terminal to where the wiper should go it wouldn't work well.

Note that Bourns numbers the terminals 2-1-3 from the back (see the drawing).