Dual 10K pot turned stepped, no ? Contact spray didn't do it? If completely gone, maybe try take apart and replace conducive parts only ?
If repair for authenticity is a no-brainer, might use a pot with detents. Maybe even just a centre-detented one for 'zero' position ?
No space for real stepped rotaries inside those units, IIRC. But last time I looked into a 722 is a few years already.