Hi Nick and Ian.
Nick - Okay, thank you for the explanation.
They both measure 0.1 ohm so I think they're making okay.
Ian and Nick - Looking at the mechanism on this particular kind of dial, I suspect that because of the way the "21" mechanism "snaps" to close the contacts during the dialling process, the 60/40 make/break may be rather more awkward (and possibly nearly impossible) to achieve than the 741 with its "54A" dial. I can see that bending the fixed contact position won't really affect the ratio (except in the wrong direction).
I think I need to be on the lookout for a "54A" dial (or just fit a Rotatone of course...).
Many thanks for all your help though Nick and Ian. It's much appreciated and I've learned a lot today.
Kind regards.
From Mike.