Well the solution turned out to be rather easy - just download the firmware to the handpad and all was well - after making a download cable and plugging an external 12v supply into the mount.
Could not get the handpad to revert to operating mode by turning off/on etc. Also, the batteries in the mount were a mix of alkaline and zinc-carbon so they did not last long.
Anyway, returned the scope to a happy owner and received a bottle of wine for my trouble.
Thanks for your help,
David.