You should be able to Ctrl/Cmd+Shift+G to Ungroup once it is in Illy. If there is a Clipping Mask or something blocking the way, you may release that. You can see it in the Layers palette.
The one from 1996 or the slightly newer one called CS6/16?
Many thanks for that its CS6/16 but it did not work.
If the PDF opens as one big image and can not be ungrouped, then it does not contain vector objects. It's just a big raster image. If you use the Direct Selection Tool (the white arrow) you should be able to select individual objects. If you can't, then it's just a raster image.