What Momo are you refering to? The Black Momo uses the plastic Pots with the ball on the end, as Gunn said. Metal pots with ball on the end, not seen or heard of those ones before.
Digi Key do do replacement pots for Black momo, and Red momo ( this uses metal pots )
I did have a link, but this is not working anymore. Give Digikey a ring, they do know what you are talking about when you mention Replacement Pots for Logitech Pedals ( they will say, you as well
)
Best of Luck