There is undoubtedly information on the various flavors of Myford at www.lathes.co.uk
A new leadscrew might be available from Myford -- I think they are still in business -- but I suspect the price would make you want to sit down.
Try to make a living, not a killing. -- Utah Phillips
Don't believe everything you know. -- Bumper sticker
Everybody is ignorant, only on different subjects. -- Will Rogers
Law of Logical Argument - Anything is possible if you don't know what you are talking about.
If at first you don't succeed, try, try, again. Then give up. There's no point in being a damn fool about it. -- W.C. Fields