Suggest you forget trying to do this your self has this rats nest would make someone with experience have to sit down and take a good hard look before delving in.!!
Best advise is Either buy modern components or hand to someone who knows what there doing.! If someone with no experience tries messing in there the outcome will be the same.???. . . You'll be buying new drives and modern components anyway because you'll have blown something up.!!
Has well as being poor performance compared to modern drives the stuff inside there is very intolerant to error and will let out the magic smoke very quickly if you miss wire or cock up.!

If it where me even thou I've got the experience to sort it I'd still be dumping that lot has the performance of modern drives would transform the machine and be much more stable/reliable and accurate with much better performance along with better quality finish.