The Fan housing is only held in place by the two bolts and spacers which go in to the heads at the top. the lower part of the cover just hangs in the air and to keep it from chafing on the cylinder fins they fit it with a piece of rubber hose split down one side. If you check you will probably find the other side with it's rubber still in place. personally I have overcome the problem by leaving the plastic nonsense under the bench in the workshop and fitted the fan in the "radiator " grille in the front of the bonnet where it can pull air through from below the car and cool the oil tank a bit as well.
Mr. Bleazey! Thank you, this made perfect sense, since I found the piece on the floor after removing and replacing the fan system. I removed it again and did not find another piece so doubtless it came off during a prior removal and reinstallation. much appreciate you sharing this.
Stephen, were your pieces fitted to the lower angle where the bottom shroud goes from horizontal to "northwest" and "northeast"?
