plotting sizes using oce9400 and autocad2002

I am using autocad2002 and plotting using oce9400.
The problem that I am having is that the file sizes are very large when I send them to the plotter (files that are about 800kB when plotted using other stations are about 4 to 5MB when I plot them on mine).
Anyone know what the problem is??

Thanks in advance

 

Unuseed blocks in the fie are my first suspect. I have had files on the order of 30-40 MB with 3D modeling involved and the plots wanting to be even larger- when I purgeed out unused blocks the plot files were a more practical size.