I had aquired some used Blue Chip made Modern Clay $1 chips a while back.
They had seen allot of use but were in good shape.
I tried using the same methods I had previously used on younger Modern Clays (and other chips). I was allways successful in removing gunk and ground in color bleed but these methods had absolutley no improvment on these tough old Blue chips.
Desperate, I eyed a bag of 0000 steel wool I had in the garage.
The results were impressive. No damage to the chip, no noticable "white dust" removed (just pink).
The inlay came out great too with no damage (in fact, I thought they were permanently faded before I restored these chips to their glory).
Before and After shots:
Emboldened by this, I tried some other similarly abrasive (but supposedly) gentle products.
All of the below products, EXCEPT the 0000 steel wool, produced chip wear and extra white dust removed from the chip.
While this worked on Blue Chips, I would caution to experiment carefully with all other chips as they are softer. Blue chips are very hard.
I hope this helps anyone with a similar situation.

Edit: the 3m "sandblaster" product worked well, but tears apart like a "magic eraser" and is not cost effective for large #'s of chips.