Update:
I've received good clear photos of the roller pairs, from which I can work out a
sufficiently accurate
diameter for the pinch roller. Thanks David and Ed.
My guess of 27.5 WAS quite a bit off. Preliminary working from the photo gives a roller
Dia of 27.2 mm,
ie only just touching. But that was done late at night, and from only one measurement.
I'll post a more detailed result later today.
Guy