Googling "magnetek gpd 333" gives a lot of hit, quite a lot of documents in English. I don't know if this is of any help, but it seems that it is the same as Yaskawa (at least manufactured by Yaskawa), which we already have a thread about but even there are some issues. Have a look at that thread and see if it gives you any information.
http://www.cnczone.com/forums/spindl...onnection.html
Anyway, not easy without a manual and perhaps it is not the most common VFD, so it isn't very strange that nobody is help you. Have you tried to contact the seller or the manufacturer?