Insane file size!

Please help.

I have generated a whole mess of library blocks that are apx. 500k
despite having almost nothing in them.
My attempts at fixing this problem include:
- Running purge & audit (2000i & 2004)
- Running recover
- isavepercent to 0
- wblock entire drawing
- wblock only the selected entities
- Manusoft SuperPurge (all)& Hard purge every entity I could think of
- Erase *  (minus my entities)
- copy clip entities out to a new drawing

The result is always the same even if I only copy clip out 1 line to a
new clean drawing the 500k comes with the 1 line!
I'm out of ideas.
Unfortunately for me I didn't notice the problem until I had  copied
this problem into 20-30 drawings.

Any thoughts appreciated.
Thanks
Zac. Kane