SandS said..
my memory is stuttering at ............." tp 10 " i think mine was
Yep, the 10 and 20 have a worm drive. The 32 has a screw drive and is incredibly robust. Even Cisco was impressed by its ruggedness.
The belt is supposed to have less than 6mm movement, 3mm each way. Mine is close to that and as I have a new belt it is worth fitting just as a service activity.