Well I fixed it, took me while as I'm not used to doing any mechanical stuff, and finding the right hex keys etc. but it was exactly as Robert had predicted, both of the set screws holding the large pulley in place on the DEC motor assembly were completely loose on their spindle, so the motor was turning but it wasn't turning the head.
Many thanks again to Robert for his help and instruction sheet, and to Tony for his helpful suggestions.
Location: southern Spain
Explore Scientific EOS-2 PMC-Eight mount
Skywatcher 200DPS Newtonian telescope
28mm 2" and 12mm 1.25" lenses.
2 and 5 x Barlows.
Huawei Android T5 Tablet
Nikon D3200 DSLR
Software: ExploreStars Android & WIndows, Stellarium OSX & Android, AstroDSLR