Naish Crapcam

After 3 Red Lines (no complaints), I bought 3 x Grand Prix. Some clever soul changed the middle cam from a traditional roller type to an alien device with 8 small plastic balls.
These have all fallen out on the 3 sails.
I have tried replacing them but they still fall out so I am reduced to robbing a (standard) roller cam from another sail to keep going.
This is far from ideal as they are (obviously) the wrong shape but better than a poke in the eye with a blunt stick I suppose.
Has anybody else had this problem ?
Any clue as to the design rationale behind this change ?
Thanks.