As for PARTS:
This site sells basic parts.
Walts (Unger Tractor) of Mexico Missouri is a source for almost any Dexta part.
Parts manuals are available on-line free with a little research. There is gentleman from Germany who play by play documented the entire rebuild to new condition of a similar early Dexta. He has a parts manual on his site. Oscars Fordson site has service manuals as well.
At this point, there is hardly a Dexta part you cannot find online. However a trip to your FNH/CNH dealer may result in that look "do I have a third eye" when you ask for Dexta parts.
Just do some research with your internet search engine.