We removed the PCL6 drivers from the server and reinstalled the printer with the PostScript drivers. After checking back with the affected users, the print jobs were now printing normally.
We have multiple users using the 5638 as a printer and all of them have reported that any documents they print are having the bottom and right of their documents cut off. We have tried the latest universal and model specific drivers to no effect. Any documents that are printed with the bottom and right cut off will print out fine on any other printer we send them to. Is there some manual scaling setting to force the print area to the paper size?