Hi phil For upgrading the mkiv mount with modern stepper motor drive systems the only company really is AWR TECHNOLOGY IN KENT drive system upgrades range from £550 -£850 for a D I Y installation professional refurbishment would be considerably more . The 1.25 inch focusser could be replaced by a revalation 2 inch crayford for £ 100 ,but would ruin it in my opinion but upgrade the focussing. Professional refurbishment would be un-economic doing it yourself really is the most sensible option .It's a difficult choice you have a lot of telescope and mount in a physical sense modernising it is un-economic and ruins it's origionality ,spliting the ota from the mount results in the same . Also they are not worth much money either compared with modern kit ,so as a complete set up they are a hard sell. And much as it pains me to say you would get more money by breaking up the entire scope and selling all of the parts separately,hate myself for saying it but this harsh reality is sadly true. If the current drives work then with a little regreasing of parts a good clean re coat the optics maybe if deteriorated . and you have a very useable scope but it needs an observatory . It's kind of is what it is a classic old school scope and mount good visual scope ,but vey expensive to upgrade and modernise ,probably not economically worth it . Selling the scope and mount separatly i wouldn't do ,i would sell all together as a complete package . So modernising this scope is expensive ,i would buy a modern scope instead . But you have a classic scope which with a little work you can use today ,in an observatory . Hope some of this rambling helps ,if you need any help or advice please P.M. me. regards clive