[lynca]

To add to versions of the tetra grabbing mechanism,

The pivot (yaw) or turret action while the robot is moving is a very crucial feature to success,

476 had a decent semi-turret
57 also had a well designed pivot motor, similar to 71

these robots can be pinned but still function because of flexible arm movement,

Also, the roll over arm seems to be quite effective as well
233 and 231 are good examples,